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  • 1.
    Guo, Li
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sandsjö, Leif
    Ortiz-Catalan, Max
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Systematic review of textile-based electrodes for long-term and continuous surface electromyography recording2020In: Textile research journal, ISSN 0040-5175, E-ISSN 1746-7748, Vol. 90, no 2, p. 227-244, article id 0040517519858768Article in journal (Refereed)
    Abstract [en]

    This systematic review concerns the use of smart textiles enabled applications based on myoelectric activity. Electromyography (EMG) is the technique for recording and evaluating electric signals related to muscle activity (myoelectric). EMG is a well-established technique that provides a wealth of information for clinical diagnosis, monitoring, and treatment. Introducing sensor systems that allow for ubiquitous monitoring of health conditions using textile integrated solutions not only opens possibilities for ambulatory, long-term, and continuous health monitoring outside the hospital, but also for autonomous self-administration. Textile-based electrodes have demonstrated potential as a fully operational alternative to ‘standard’ Ag/AgCl electrodes for recording surface electromyography (sEMG) signals. As a substitute for Ag/AgCl electrodes fastened to the skin by taping or pre-gluing adhesive, textile-based electrodes have the advantages of being soft, flexible, and air permeable; thus, they have advantages in medicine and health monitoring, especially when selfadministration, real-time, and long-term monitoring is required. Such advances have been achieved through various smart textile techniques; for instance, adding functions in textiles, including fibers, yarns, and fabrics, and various methods for incorporating functionality into textiles, such as knitting, weaving, embroidery, and coating. In this work, we reviewed articles from a textile perspective to provide an overview of sEMG applications enabled by smart textile strategies. The overview is based on a literature evaluation of 41 articles published in both peer-reviewed journals and conference proceedings focusing on electrode materials, fabrication methods, construction, and sEMG applications. We introduce four textile integration levels to further describe the various textile electrode sEMG applications reported in the reviewed literature. We conclude with suggestions for future work along with recommendations for the reporting of essential benchmarking information in current and future textile electrode applications.

  • 2.
    Kadi, Nawar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business. University of Borås.
    Effect of Textile structure in the process parameters of thermoplastic bio-composite2019In: MATEC Web of Conferences, E-ISSN 2261-236X, Vol. 261, no 01005, p. 1-3Article in journal (Other academic)
    Abstract [en]

    Thermoplastic bio-composite have a higher potential of use based on the sustainability benefits. Natural fibres today are a popular choice for applications in biocomposite manufacturing. Hybrid yarns are a satisfactory solution to improve the fabrication of composites containing a thermoplastic matrix and plant-based fibres. Nevertheless, it is still difficult to produce bio-composites with superior mechanical properties, due to problematic impregnation and consolidation results during the production process. This paper investigates the processing parameters for the compression moulding of two different hemp/PLA textiles structure bio-composites (warp knitting and weaving structure). Finite element simulations are used to optimise the processing parameters (pressure, temperature, and time). The results demonstrated that the textile structure has a small effect on the time of production. Main while the pressure and temperature of processing parameters depend only on the type of matrix and the thickness of biocomposite has a big impact on the time of production.

  • 3.
    Jabbari, Mostafa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lundin, Magnus
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bahadorikhalili, S
    Department of Chemistry, Ångström Laboratory, Uppsala University.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Finding solvent for polyamide 11 using a computer software2019In: Zeitschrift für Physikalische Chemie, ISSN 0942-9352Article in journal (Refereed)
    Abstract [en]

    The solvent finding step has always been a time-consuming job in chemical-involved processes. The source of difficulty mainly comes from the trial-and-errors, as a repetitive process of chosing solvents and mixing them in different proportions. Computers are good at doing repetitive processes; however, they can only deal with numerical values, rather than qulitative scales. Numerification of qualitative parameters (like solubility) has already been introduced. The most recent one is the Hansen solubility parameters (HSPs). Using the HSPs could provide a solvent or solvent-mixture. In our previous study, we introduced a computer-aided model and a software to find a solvent mixture. In this study, we have used the computer-aided solvent selection model to find some solvent mixtures for polyamide 11, a biobased polymer which has attracted enormous attention recently. Using this numerical model significantly diminished the time of solvent development experimentation by decreasing the possible/necessary trials.

  • 4.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajan, Rathish
    Tampere University.
    Periyasamy, Aravin Prince
    Technical University of Liberec.
    Mechanical performance of biofibers and their corresponding composites2019In: Mechanical and Physical Testing of Biocomposites, Fibre-Reinforced Composites and Hybrid Composites / [ed] Mohammad Jawaid, Mohamed Thariq, Naheed Saba, Woodhead Publishing Limited, 2019Chapter in book (Refereed)
    Abstract [en]

    This chapter focuses on mechanical performance of biofibers such as flax, hemp, and sisal and their effect on mechanical performance when they are reinforced in thermoset and thermoplastic polymers. The aim of this chapter is to present an overview of the mechanical characterization of the biofibers and their corresponding composites. The mechanical characterization includes tensile, flexural, impact, compressive, shear, toughness, hardness, brittleness, ductility, creep, fatigue, and dynamic mechanical analyses. Detailed studies of each test have been widely reported and an overview is important to relate the studies. Studies pertaining to the topics are cited. The most common materials used in biocomposites are biofibers (also called natural fibers) and petroleum-based polymers such polypropylene. The use of renewable materials in biocomposites has increased in the past couple of decades owing to extensive research on cellulosic fibers and biopolymers based on starch or vegetable oil. Today, research is focused on reinforcing natural fibers in petroleum-based polymers. However, the emphasis is shifting toward the amount of renewable materials in biocomposites, which has led to the use of biopolymers instead of petroleum-based polymers in composites. The mechanical properties of some renewable resource-based composites are comparable to commercially available nonrenewable composites.

    Several plant biofibers have been reinforced in thermoplastics or thermosets to manufacture biocomposites because of their specific properties. The Young's modulus of commonly used biofibers such as hemp and flax could be over 50 GPa and therefore they could be good alternatives to glass fibers in several applications. The good mechanical properties of these biofibers influence the composites' mechanical performance when reinforced in polymers. It is important to understand the mechanical performance of these biofibers and biocomposites in a working environment. A detailed discussion about the mechanical performance of commonly used biofibers and composites is provided in this chapter.

  • 5.
    Soroudi, Azadeh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Novel Skin-Electrode Conductive Adhesives to Improve the Quality of Recorded Body Signals in Smart Medical Garments2019In: Proceedings, ISSN 2504-3900, Vol. 32Article in journal (Refereed)
    Abstract [en]

    A main barrier to widespread use of electrocardiography garments for long term heart monitoring of elderly and patients is a poor skin-electrode signal transfer because of a high contact impedance and sensitivity to movement. This leads to unwanted disturbances and errors in recorded signals when the patient moves or even breathe, affecting the reliability and quality of the signals especially for patients with dry/old skin. In two different projects at the University of Borås, we have developed two novel products to solve the above problem; (1) an ongoing project that has fabricated a reusable and sustainable electro-conductive adhesive applicable between the skin and high-porous textile electrodes, and (2) a patent-pending skin-electrode glue (BioEl Glue®) which is a biocompatible electro-conductive water-soluble glue used between skin and low-porous textile electrodes.

  • 6.
    Jabbari, Mostafa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lundin, Magnus
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hatamvand, M
    Computer Science and Mathematics Faculty, Bielefeld University of Applied Sciences.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Computer-aided theoretical solvent selection using the simplex method based on Hansen solubility parameters2018In: Journal of Information Technology & Software Engineering, Vol. 8, no 4, article id 1000242Article in journal (Refereed)
    Abstract [en]

    Solvent selection is a crucial step in all solvent-involved processes. Using the Hansen solubility parameters (HSPs)could provide a solvent/solvent-mixture, but there are two main challenges: 1) What solvents should be selected? 2)From each solvent, how much should be added to the mixture? There is no straightforward way to answer the twochallenging questions. This contribution proposes a computer-aided method for selecting solvents (answer to thequestion 1) and finding the adequate amount of each solvent (answer to the question 2) to form a mixture of 2, 3 or4 solvents to dissolve a solute with known HSPs or to replace a solvent. To achieve this, a sophisticated computersoftware package was developed to find the optimized mixture using the mathematical Simplex algorithm based onHSPs values from a database of 234 solvents. To get a list of solvent-mixtures, polyamide66 was tested using itsHSPs. This technique reduces the laboratory effort required in selecting and screening solvent blends while allowinga large number of candidate solvents to be considered for inclusion in a blend. The outcome of this paper significantlydiminished the time of solvent development experimentation by decreasing the possible/necessary trials. Thus, themost suitable solvent/solvent-substitution can be found by the least possible effort; hence, it will save time and costof all solvent-involved processes in the fields of chemistry, polymer and coating industries, chemical engineering, etc.

  • 7.
    Vogt, Sarah
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Determination of Processing Parameters for Thermoplastic Biocomposites Based on Hybrid Yarns Using Finite Elements Simulation2018In: Journal of Composites Science, ISSN 2504-477X, Vol. 2, no 1Article in journal (Refereed)
    Abstract [en]

    This paper investigates the processing parameters for the compression molding of hemp/PLA hybrid yarn biocomposites and their effect on the final mechanical properties. Finite element simulations are used to develop and assess the processing parameters, pressure, temperature, and time. These parameters are then evaluated experimentally by producing the composites by two different methods, to compare the results of experimentally determined processing conditions to parameters determined by the simulation analysis. The assessment of mechanical properties is done with several experimental tests, showing small improvements for the composites produced with the simulation method. The application of the simulation analysis results in considerably reduced processing times, from the initial 10 min to only three minutes, thereby vastly improving the processing method. While the employed methods are not yet able to produce composites with greatly improved mechanical properties, this study can be seen as a constructive approach, which has the ability to lead to further improvements.

  • 8.
    Temmink, Robin
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Development of biocomposites from denim waste and thermoset bio-resins2018In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 106, p. 59-69Article in journal (Refereed)
    Abstract [en]

    This paper examines the use of post-consumer denim fabric in combination with thermoset bio-resins in composite manufacturing for structural applications. Bio-epoxy and acrylated epoxidized soybean oil resin (AESO) were used as bio-resins with four different manufacturing techniques in order to create a wide scope of possibilities for research. The four techniques are: compression moulding (COM), vacuum infusion (VAC), resin transfer moulding (RTM) and hand lay-up (HND). The bio-resins were compared to a conventional polyester resin, as this is highly used for structural applications. To determine suitability for structural applications, the biocomposites were tested for their mechanical and thermal properties. Fabricated composites were characterised regarding porosity, water absorption and analysed through microscopic images of the composite. Results show both bio-epoxy and AESO are suitable for use in structural applications over a range of manufacturing techniques. Furthermore, biocomposites from bio-epoxy are superior to those from AESO resin. The conventional polyester has shown to be unsuitable for structural applications.

  • 9.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajan, Rathish
    Tampere University of Technology.
    Rainosalo, Egidija
    Centria University of Applied Sciences.
    Thomas, Selvin
    Yanbu Industrial College and Advanced Materials Laboratory.
    Zavasnik, Janez
    Jožef Stefan Institute.
    Vuorinen, Jyrki
    Tampere University of Technology.
    Mechanical, thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification2018In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 135, no 36Article in journal (Refereed)
    Abstract [en]

    The influence of epoxy resin modification by 3-aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained forAPTES-modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES-modified viscose fabric. The dynamic mechanical behavior of the APTES-modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other compo-sites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications.

  • 10.
    Rajan, Rathish
    et al.
    Tampere University of Technology.
    Rainosalo, Egidija
    Centria University of Applied Sciences.
    Thomas, Selvin
    Royal Commission Yanbu Colleges and Institutes.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Vuorinen, Jyrki
    Tampere University of Technology.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Zavasnik, Janez
    Jožef Stefan Institute.
    Modification of epoxy resin by silane-coupling agent to improve tensile properties of viscose fabric composites2018In: Polymer Bulletin, ISSN 0170-0839, E-ISSN 1436-2449, Vol. 75, no 1, p. 167-195Article in journal (Refereed)
    Abstract [en]

    The modification of epoxy resin by 3-aminopropyltriethoxysilane (APTES) to improve the tensile properties of warp knitted viscose fabric composites is reported in this study. The study evaluates the efficiency of modification methods adopted to modify the epoxy resin and the influence of the resin modification on various properties of the cured castings. The influence of matrix resin modification on the tensile properties of viscose fabric composite is compared to those prepared from chemically modified fibre. The efficiency of the modification was determined through titration method to determine the epoxide content of epoxy resin, viscosity measurement and FTIR. The effect of APTES modification on various properties of cured castings is studied through differential scanning calorimeter, contact angle measurement and tensile testing. The addition of APTES into the epoxy resin decreased the epoxide content in the resin as evident from the titration method. The tensile strength of cured castings decreased after the resin modification. The tensile strength and elongation at break of the viscose fabric composites prepared from modified resin, increased up to 14 and 41%, respectively. The improved adhesion of APTES-modified epoxy resin to the viscose fibre is confirmed from SEM analysis of tensile fracture surface.

  • 11.
    Jabbari, Mostafa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    New Solvent for Polyamide 66 and Its Use for Preparing a Single-Polymer Composite-Coated Fabric2018In: International Journal of Polymer Science, ISSN 1687-9422, E-ISSN 1687-9430Article in journal (Refereed)
    Abstract [en]

    Polyamides (PAs) are one of the most important engineering polymers; however, the difficulty in dissolving them hinders their applications. Formic acid (FA) is the most common solvent for PAs, but it has industrial limitations. In this contribution, we proposed a new solvent system for PAs by replacing a portion of the FA with urea and calcium chloride (FAUCa). Urea imparts the hydrogen bonding and calcium ion from the calcium chloride, as a Lewis acid was added to the system to compensate for the pH decrease due to the addition of urea. The results showed that the proposed solvent (FAUCa) could readily dissolve PAs, resulting in a less decrease in the mechanical properties during the dissolution. The composite prepared using the FAUCa has almost the same properties as the one prepared using the FA solution. The solution was applied on a polyamide 66 fabric to make an all-polyamide composite-coated fabric, which then was characterized. The FAUCa solution had a higher viscosity than the one prepared using the neat FA solvent, which can be an advantage in the applications which need higher viscosity like preparing the all-polyamide composite-coated fabric. A more viscous solution makes a denser coating which will increase the water /gas tightness. In conclusion, using the FAUCa solvent has two merits: (1) replacement of 40% of the FA with less harmful and environmentally friendly chemicals and (2) enabling for the preparation of more viscous solutions, which makes a denser coating.

  • 12.
    Kadi, Nawar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Muhandes, HasanKalácska, GáborSkrifvars, MikaelUniversity of Borås, Faculty of Textiles, Engineering and Business.
    Pin-on-Plate Abrasive Wear Test For Several Composite Materials2018Conference proceedings (editor) (Refereed)
  • 13.
    Kadi, Nawar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, BehnazUniversity of Borås, Faculty of Textiles, Engineering and Business.Skrifvars, MikaelUniversity of Borås, Faculty of Textiles, Engineering and Business.
    The effect of process parameters on the mechanical properties of thermoplastic bio-composite2018Conference proceedings (editor) (Refereed)
  • 14.
    Kadi, Nawar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Using Finite Element Simulation to Optimize Thermoplastic Bio - Composites Process Parameters2018In: International Journal of Management and Applied Science, ISSN 2394-7926, Vol. 4, p. 73-75Article, book review (Refereed)
    Abstract [en]

    The use of thermoplastic composite is clearly of higher potential because of: good impact strength, easier recycling, faster processing conditions (no time for curing is required), possibility of production in longer series, lower cost, absence of toxic solvents and higher fracture toughness and elongation on the fracture. Natural fibres today are a popular choice for applications in composite manufacturing. In fact, a major challenge for natural fibre reinforced composites is to achieve high mechanical performance at competitive prices. This paper investigates the processing parameters for the compression moulding of hemp/PLA hybrid yarn bio-composites and their effect on the final mechanical properties. Finite element simulations are used to develop and assess the processing parameters pressure, temperature, and time. The application of the simulation analysis results in considerably reduced the processing times from initially 10 minutes to only 2 minutes, and improved the mechanical bio-composite

  • 15.
    Asadi, Milad
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bashir, Tariq
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Development of eco-friendly flame retardant polypropylene fibers2017Conference paper (Refereed)
  • 16.
    Kalantar Mehrjerdi, Adib
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Naudin, Sébastien
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Development of Polyolefin Compound and Post-Polymerization Treatments for Ground Heat Exchangers2017Conference paper (Refereed)
    Abstract [en]

    A ground source heat pump (GSHP) system can be used for both cooling and heating modes simultaneously for commercial, industrial and residential buildings virtually at any location with great flexibility to cover a wide range of demands all around the world. Polyethylene (PE) has been used as the main raw material in production of the Ground Heat Exchangers (GHE). This paper briefly reviews the history of polyethylene and development in polymerization process with emphasis on the third-generation bimodal structure. The characteristics of PE pipes used in GSHP systems are discussed. This paper is devoted to a critical review on the attempts in post-polymerization treatments of the PE, and GHEs to improve the performance of the systems. The experimental and simulated comparisons show that the enhancement of the thermal conductivity of the material can reduce significantly the overall borehole thermal resistance.

  • 17.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pal, Jit
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi, India.
    Srivastava, Rajiv K
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi, India.
    Nandan, Bhanu
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi, India.
    Electrospun composite matrices from tenside-free poly(caprolactone)-grafted acrylic acid/hydroxyapatite oil-in-water emulsions2017In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, no 4, p. 2254-2262Article in journal (Refereed)
    Abstract [en]

    Composite matrices of poly(ε-caprolactone)-grafted acrylic acid (PCL-g-AA) and hydroxyapatite (HA) were prepared via electrospinning of oil-in-water emulsions. Grafting of varying amounts of AA on PCL was carried out in a twin-screw compounder using benzoyl peroxide as an initiator under inert atmosphere. A solution of PCL-g-AA in toluene, containing HA, comprised the oil phase of the emulsion, while the aqueous phase contained poly(vinyl alcohol) (PVA) as a template polymer. No emulsifier was used in making such emulsions which were found to be stable for more than a month at room temperature. Secondary interactions of AA group of PCL-g-AA with HA and PVA at the oil–water interface provided stability to the emulsion. Uniform composite fibrous matrices were produced from the resultant emulsions under controlled electrospinning conditions. The composite matrices, thus developed using minimal organic solvent, are free from emulsifiers and have high potential to be used in applications including tissue engineering

  • 18.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Alagar, Ragunathan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Akhtar, Naeem
    University of Borås, Faculty of Textiles, Engineering and Business.
    End of life textiles as reinforcements in biocomposites2017In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, p. -12Article in journal (Refereed)
    Abstract [en]

    A number of attempts have been made to recycle cotton/polyester blend woven fabrics after use; however, most of these fabrics are disposed of in landfills. Major part of these blend fabrics are not recycled due to complexity of the fibre arrangement and cannot be separated economically. This study shows that these discarded woven fabrics could be directly used as reinforcements in composites without fibre separation. Uniform alignment in the woven fabric provided consistent properties to the composites. The fabrics were reinforced by soybean-based-bioresins to produce biocomposites. The composites were analysed for mechanical, thermal, viscoelastic and morphological properties. Porosity and wettability of the composites were also evaluated. Results demonstrate that the tensile strength and modulus of over 100 and 10 MPa, respectively, can be obtained without any fibre treatment. Furthermore, impact strength over 70 kJ/m2 was obtained without any chemical treatment on fibres. The porosity of the composites produced was less than 9 vol%. Additionally, the fabrics were treated with alkali in order to improve the fibre–matrix interface and the composite properties were studied. From the economical perspective, these composites can be produced at a low cost as the major component is available for free or low cost.

  • 19.
    Hatamvand, Mohammad
    et al.
    Yazd University.
    Mirjalili, Seyed Abbas
    Yazd University.
    Sharzehee, Maryam
    Yazd University.
    Behjat, Abbas
    Yazd University.
    Jabbari, Mostafa
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fabrication parameters of low-temperature ZnO-based hole-transport-free perovskite solar cells2017In: Optik (Stuttgart), ISSN 0030-4026, E-ISSN 1618-1336, Vol. 40, p. 443-450Article in journal (Refereed)
    Abstract [en]

    Perovskite solar cells (PSCs) are a new generation solar cells. Low-Temperature techniques are used for fabrication PSCs on a flexible substrate that has a low thermal tolerance. In this paper, low-temperature PSCs with ZnO nanoparticles were prepared as electron transport material (ETM) without hole transport material (HTM). Effects of some of the fabrication parameters of low-temperature ZnO based PSCs without HTM, on their principal characteristics and performance, were investigated. Parameters such as the concentration of ZnO nanoparticles (NPs) dispersion, spin coating speed of ZnO NPs, and concentration of CH3NH3I on characteristics and performance of fabricated low-temperature PSCs were studied. The study shows that by changing these parameters, the performance of the fabricated PSCs changes considerably.

  • 20.
    Bashir, Tariq
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Persson, Nils-Krister
    University of Borås, Faculty of Textiles, Engineering and Business.
    High-strength electrically conductive fibers: functionalization of polyamide, aramid and polyester fibers with PEDOT polymer2017In: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581, Vol. 29, no 1, p. 310-318, article id 10.1002/pat.4116Article in journal (Refereed)
    Abstract [en]

    In this work, high-performance fibers such as aramid (Twaron), polyamide (PA6), polyester (PET), and hybrid Twaron/PA6 fibers were transformed into electroactive fibers by coating them with conjugated polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) through vapor phase polymerization (VPP) method. The VPP is considered as an efficient technique for depositing CPs on different substrates regardless of their lower solubility in various solvents. In this paper, PEDOT-coated high-performance fibers were prepared under already optimized reaction conditions, and then a comparison between electrical, thermal, and mechanical properties of different fibers, before and after coating, was made. The obtained coated fibers were characterized through scanning electron microscope (SEM), thermogravimetric analysis (TGA), 2-probe electrical resistance measurement method, and tensile testing. It was revealed that at particular reaction conditions, all high performance textile substrates were successfully converted into electroactive fibers. The voltage-current (V-I) characteristics showed that PEDOT-coated polyester fibers exhibited highest conductivity value among all other substrate fibers. The active PEDOT layers on high performance fibers could behave as an antistatic coating to minimize the risks associated with static charges at work places. Also, the obtained fibers have potential to be used as smart materials for various medical, sports, and military applications.

  • 21.
    Persson, Nils-Krister
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Persson, Nils-Krister
    University of Borås, Faculty of Textiles, Engineering and Business.
    High-strengthelectrically conductive fibers: Functionalization of polyamide, aramid andpolyester fibers with PEDOT polymer2017In: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581Article in journal (Refereed)
    Abstract [en]

    In this work, high-performance fibers such as aramid (Twaron), polyamide (PA6), polyester (PET), and hybrid Twaron/PA6 fibers were transformed into electroactive fibers by coating them with conjugated polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) through vapor phase polymerization (VPP) method. The VPP is considered as an efficient technique for depositing CPs on different substrates regardless of their lower solubility in various solvents. In this paper, PEDOT-coated high-performance fibers were prepared under already optimized reaction conditions, and then a comparison between electrical, thermal, and mechanical properties of different fibers, before and after coating, was made. The obtained coated fibers were characterized through scanning electron microscope (SEM), thermogravimetric analysis (TGA), 2-probe electrical resistance measurement method, and tensile testing. It was revealed that at particular reaction conditions, all high performance textile substrates were successfully converted into electroactive fibers. The voltage-current (V-I) characteristics showed that PEDOT-coated polyester fibers exhibited highest conductivity value among all other substrate fibers. The active PEDOT layers on high performance fibers could behave as an antistatic coating to minimize the risks associated with static charges at work places. Also, the obtained fibers have potential to be used as smart materials for various medical, sports, and military applications.

  • 22.
    Hatamvand, Mohammad
    et al.
    Yazd University.
    Abbas Mirjalili, Seyed
    Yazd University.
    Fattahi, Saeid
    Yazd University.
    Bashir, Tariq
    Yazd University.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Optimum Drafting Conditions of Polyester and Viscose Blend Yarns2017In: AUTEX Research Journal, ISSN 1470-9589, E-ISSN 2300-0929Article in journal (Refereed)
    Abstract [en]

    In this study, we used an experimental design to investigate the  influence of the total draft, break draft, distance between the aprons (Clips) and production roller pressure on yarn quality in order to obtain optimum drafting conditions for polyester and viscose (PES/CV) blend yarns in ring spinning frame. We used PES fibers (1.4 dtex × 38 mm long) and CV fibers (1.6 dtex × 38 mm long) to spin a 20 Tex blend yarn of PES (70%)/CV (30%) blend ratio. When the break draft, adjustment of distance between of aprons and roller pressure is not reasonable, controlling and leading of the fibers is not sufficient for proper orientation of the fibers in the yarn structure to produce a high quality yarn. Experimental results and statistical analysis show that the best yarn quality will be obtained under drafting conditions total draft of 38, 1.2 break draft, 2.8 mm distance between of aprons and maximum pressure of the production top roller (18daN).

  • 23.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Preparation and Characterization of Biobased Thermoset Polymers from Renewable Resources and Their Use in Composites2017In: Handbook of Composites from Renewable Materials, Physico-Chemical and Mechanical Characterization / [ed] Vijay Kumar Thakur, Manju Kumari Thakur, Michael R. Kessler, Hoboken, New Jersey, USA: John Wiley & Sons, 2017, p. 425-457Chapter in book (Refereed)
    Abstract [en]

    This chapter focuses on physicochemical and mechanical characterization of compositesmade from renewable materials. Most common renewable materials used in composites arenatural fibers and polymers based on starch or vegetable oil. The extent of using renewablematerials in biocomposites has increased during the past decade due to extensive research oncellulosic fibers and biobased polymers. Earlier, the research was focused on using the naturalfibers as reinforcement in crude oil-based polymers such as polypropylene. Later, the emphasisshifted to increase the amount of renewable components in the biocomposites which led tothe introductionof biobased resins in the composites. The properties of some biocompositesare today comparable to the properties for commercially available nonrenewable composites.Several plant biofibers have been used as reinforcement in biobased thermoplastics or thermosetsto manufacture biocomposites. Material characterization is important to understand theperformance of these composites under specific environment. Detailed discussion about themechanical and physicochemical characterization is provided in this chapter. Physicochemicalcharacterization includes chemical composition, density, viscosity, molecular weight, meltingtemperature, crystallinity,morphology, wettability, surface tension, water binding capacity,electricalconductivity, flammability, thermal stability, and swelling. Mechanical characterizationincludes tensile, flexural, impact, compressive, shear, toughness, hardness, brittleness, ductility,creep, fatigue, and dynamic mechanical analysis.

  • 24.
    Baghaei, Behnaz
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Temmink, Robin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    RECYCLING OF END-OF-LIFE TEXTILE MATERIALS BY FABRICATION OF GREEN COMPOSITES2017Conference paper (Refereed)
    Abstract [en]

    Material recycling requires rather pure and non-contaminated waste streams, which can be converted by technical processes into new materials and products by economically and technically feasible techniques. It is also required that there is a secondary market for these recycled materials, and preferably in use areas with high economic value. End-of-life textiles cannot yet be recycled as a raw material in a feasible way. Structural composites are an excellent use area for recycled materials, as they are durable and light-weight products, with excellent mechanical properties.

    In this study, denim woven fabrics as end-of-life textiles were employed to improve the mechanical and thermal properties of high bio-content epoxy resin. Entropy Resin, manufacturer of commercial bio-based epoxy resin, claimed that bio-based content of system is 37 % and the resin is derived from by-products of industrial processes including wood pulp and biofuel. Bioepoxy was used as bio resins in composite manufacturing, and a conventional polyester resin served as a reference material. To create a wide scope of possibilities the composites were manufacturing using the four techniques: (1) vacuum infusion (VI), (2) resin transfer moulding (RTM), and (3) hand lay-up (HND). To determine the suitability for structural applications the biocomposites were tested for their mechanical and thermal properties. Mechanical tests for tensile, flexural strength and impact behaviour were conducted on composites. Moreover, viscoelastic properties of the composites were evaluated through dynamic mechanical analysis (DMA). Fabricated composites were characterised regarding porosity, water absorption and analysed through microscopic images of the composite cross section. Different manufacturing technique showed varying results. For bioepoxy both HND and VI give superior mechanical properties over RTM, as the latter gives a higher void content, and lower tensile and flexural properties.

  • 25.
    Fazelinejad, Samaneh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Repeated mechanical recycling of polylactic acid filled with chalk2017In: Progress in Rubber, Plastics and Recycling Technology, ISSN 0266-7320, E-ISSN 1478-2413, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Polylactic acid (PLA) was compounded with 30 wt% chalk and 5 wt% of a biobased plasticiser on a twin screw extruder. Mechanical recycling of the obtained compound was studied by multiple extrusions up to six cycles. The degradation was monitored by mechanical and thermal tests. Tensile and flexural tests did not reveal any major degradation after six cycles of processing. Characterising the material with differential scanning calorimetry (DSC) did not detect any significant change of the thermal properties. The material was also characterised by FTIR and, again, no significant change was detected. The material was finally characterised by melt flow index and by proton nuclear magnetic resonance (1H-NMR). Both tests revealed that some degradation had occurred. The 1H-NMR clearly showed that the chain length had been reduced. Also, the MFI test showed that degradation had occurred. However, the study reveals that PLA filled with chalk can be recycled by repeated extrusion for up to 6 cycles, without severe degradation. This should be of relevance when considering the end-of-life treatment of polymer products made from PLA.

  • 26.
    Esmaeili, Nima
    et al.
    University of Bolton.
    Jahandideh, Arash
    South Dakota State University.
    Muthukumarappan, Kasiviswanathan
    South Dakota State University.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Synthesis and characterization of methacrylated star-shaped poly(lactic acid) emplying core moilecules with different hydroxyl groups2017In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 134, no 39, article id 45341Article in journal (Refereed)
    Abstract [en]

    A set of novel bio-based star-shaped thermoset resins was synthesized via ring-opening polymerization of lactide and employing different multi-hydroxyl core molecules, including ethylene glycol, glycerol, and erythritol. The branches were end-functionalized with methacrylic anhydride. The effect of the core molecule on the melt viscosity, the curing behavior of the thermosets and also, the thermomechanical properties of the cured resins were investigated. Resins were characterized by Fourier-transform infrared spectroscopy, 13C-NMR, and 1H-NMR to confirm the chemical structure. Rheological analysis and differential scanning calorimetry analysis were performed to obtain the melt viscosity and the curing behavior of the studied star-shaped resins. Thermomechanical properties of the cured resins were also measured by dynamic mechanical analysis. The erythritol-based resin had superior thermomechanical properties compared to the other resins and also, lower melt viscosity compared to the glycerol-based resin. These are of desired characteristics for a resin, intended to be used as a matrix for the structural composites. Thermomechanical properties of the cured resins were also compared to a commercial unsaturated polyester resin and the experimental results indicated that erythritol-based resin with 82% bio-based content has superior thermomechanical properties, compared to the commercial polyester resin. Results of this study indicated that although core molecule with higher number of hydroxyl groups results in resins with better thermomechanical properties, number of hydroxyl groups is not the only governing factor for average molecular weight and melt viscosity of the uncured S-LA resins.

  • 27.
    Kadi, Nawar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Peterson, Joel
    University of Borås, Faculty of Textiles, Engineering and Business.
    Holmudd, Olle
    University of Borås, Faculty of Textiles, Engineering and Business.
    Karnoub, Amer
    University of Aleppo.
    The Effect of Warp Tension on the Colour of Jacquard Fabric2017In: IOP Conference Series: Materials Science and Engineering, 2017, Vol. 254, article id 082014Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    The aims of this paper is to demonstrate the effect of warp tension on fabric colour for several types of weaves structures, and found a relationship between them. The image analyse technique used to determine the proportion of yarns colour appearance, the advantage of this techniques is the rapidity and reliability. The woven fabric samples are consisting of a polyester warp yarn with continuous filaments and density of 33 end/cm, a polypropylene weft yarn with a density of 24 pick/cm, and the warp tension ranged between 12-22 cN/tex. The experimental results demonstrated the effect of the warp tension on the colour of fabric, and this effect is related to several factors, where the large proportion of warp appearance leads to larger effect on fabric colour. The difference in the value of colour differences ΔEcmc is larger is in the range 16 to 20 cN/tex of warp tension. Using statistical methods, a mathematical model to calculate the amount of the colour difference ΔEcmc caused by the change in warp tension had been proposed.

  • 28.
    Karnoub, Amer
    et al.
    Faculty of Mechanical Engineering, University of Aleppo.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Holmudd, Olle
    University of Borås, Faculty of Textiles, Engineering and Business.
    Peterson, Joel
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    The Effect of Warp Tension on the Colour of Jacquard Fabric Made with Different Weaves Structures2017In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 254Article in journal (Refereed)
    Abstract [en]

    The aims of this paper is to demonstrate the effect of warp tension on fabric colour for several types of weaves structures, and found a relationship between them. The image analyse technique used to determine the proportion of yarns colour appearance, the advantage of this techniques is the rapidity and reliability. The woven fabric samples are consisting of a polyester warp yarn with continuous filaments and density of 33 end/cm, a polypropylene weft yarn with a density of 24 pick/cm, and the warp tension ranged between 12-22 cN/tex. The experimental results demonstrated the effect of the warp tension on the colour of fabric, and this effect is related to several factors, where the large proportion of warp appearance leads to larger effect on fabric colour. The difference in the value of colour differences ΔEcmc is larger is in the range 16 to 20 cN/tex of warp tension. Using statistical methods, a mathematical model to calculate the amount of the colour difference ΔEcmc caused by the change in warp tension had been proposed.

  • 29.
    Kadi, Nawar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Muhandes, Hasan
    Kalácska, Gábor
    Thermoplastic biocomposite based on cellulose fibers2017Conference paper (Refereed)
  • 30.
    Santamala, Harri
    et al.
    Aalto University, School of Engineering, Department of Applied Mechanics.
    Livingston, R
    Aalto University, School of Engineering, Department of Applied Mechanics.
    Sixta, Herbert
    Aalto University, Aalto University, School of Chemistry, Department of Forest Products Technology.
    Hummel, M
    Aalto University, School of Chemistry, Department of Forest Products Technolog.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Saarela, Olli
    Aalto University, School of Engineering, Department of Applied Mechanics.
    Advantages of regenerated cellulose fibres as compared to flax fibres in the processability and mechanical performance of thermoset composites2016In: Composites Part A: Applied Science and Manufacturing, ISSN 1359-835X, Vol. 84, p. 377-385Article in journal (Refereed)
    Abstract [en]

    Man-made cellulosic fibres (MMCFs) have attracted widespread interest as the next generation of fibre reinforced composite. However, most studies focused entirely on their performance on single fibre level and little attention has been paid to their behaviour on a larger application scale. In this study, MMCFs were utilized as reinforcement in unidirectionally (UD) manufactured thermoset composites and compared to several commercial UD flax fibre products. Specimens were prepared using a vacuum bag based resin infusion technique and the respective laminates characterized in terms of void fraction and mechanical properties. MMCF laminates had comparable or better mechanical performance when compared to flax fibre laminates. Failure mechanisms of MMCF laminates were noted to differ from those of flax-reinforced laminates. The results demonstrate the potential of MMCFs as a viable alternative to glass fibre for reinforcement on a larger scale of UD laminates. These results were utilized in the Biofore biomaterial demonstration vehicle.

  • 31.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    BIOCOMPOSITES FROM SURFACE MODIFIED REGENERATED CELLULOSE FIBERS AND LACTIC ACID THERMOSET BIORESIN2016Conference paper (Refereed)
    Abstract [en]

    Abstract:

    Thermoset bioresin was synthesized from lactic acid and glycerol, and the resin was characterized for it to be used in composite applications. On the other hand, regenerated cellulose fibers were surface treated to improve the physico–chemical interactions at the fiber–matrix interface. The effect of surface treatments, silane and alkali, on regenerated cellulose fibers was studied by using the treated fibers as reinforcement in lactic acid thermoset bioresin. Mechanical tests were used as indicator of the improvement of the interfacial strength. Fiber surface treatments and the effect on adhesion to the matrix were characterized using microscopy images and thermal conductivity. Mechanical properties of the composites showed an increase when treated with silane as the bi-functional silane molecule acts as link between the regenerated cellulose fiber and the bioresin.

    Porosity volume decreased significantly on silane treatment due to improved interface and interlocking between fiber and matrix. Decrease in water absorption and increase in contact angle confirmed the change in the hydrophilicity of the composites. The storage modulus increased when the reinforcements were treated with silane whereas the damping intensity decreased for the same composites indicating a better adhesion between fiber and matrix on silane treatment. Thermogravimetric analysis indicated that the thermal stability of the reinforcement altered after treatments. The resin curing was followed using differential scanning calorimetry and the necessity for post-curing was recommended. Finite element analysis was used to predict the thermal behavior of the composites and a non-destructive resonance analysis was performed to ratify the modulus obtained from tensile testing. The changes were also seen on composites reinforced with alkali treated fiber. Microscopy images confirmed the good adhesion between the silane treated fibers and the resin at the interface.

  • 32.
    Baghaei, Behnaz
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Characterisation of polylactic acid biocomposites made from prepregs composed of woven polylactic acid/hemp–Lyocell hybrid yarn fabrics2016In: Composites Part A: Applied Science and Manufacturing, ISSN 1359-835X, Vol. 81, p. 139-144Article in journal (Refereed)
    Abstract [en]

    This paper describes the mechanical properties and water absorption characteristics for biocomposites made from woven PLA/hemp/Lyocell prepregs. The aim was to improve the properties with the addition of Lyocell fibre into a hybrid yarn. Well-aligned hybrid yarns composed of hemp/PLA, hemp-Lyocell/PLA, respective, Lyocell/PLA were made by wrap spinning. Unidirectional satin fabrics were made by weaving with PLA (warp) and the hybrid yarns (weft). Uniaxial composites were fabricated with 30 fibre mass% using compression moulding. The composites were investigated for tensile, flexural and impact properties. Combining hemp with Lyocell in a PLA matrix improves the mechanical properties, compared to hemp/PLA composites. The composite made from the satin Lyocell/PLA fabric gave the best mechanical properties. The type of fibre reinforcement compositions did not significantly affect the water absorption of the biocomposites. Scanning electron microscopy showed that fibre pull-outs appear more often in hemp/PLA composites than in composites also including Lyocell fibre. © 2015 Elsevier Ltd. All rights reserved.

  • 33.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dhakal, Hom
    Advanced Polymer and Composites (APC) Research Group, University of Portsmouth, Portsmouth, UK.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Zhang, Z
    Advanced Polymer and Composites (APC) Research Group, University of Portsmouth, Portsmouth, UK.
    Hybrid composites and biocomposites: concepts, opportunities and research challenges2016Conference paper (Refereed)
  • 34.
    Jabbari, Mostafa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Introducing all-polyamide composite coated fabrics: A method to produce fully recyclable single-polymer composite coated fabrics2016In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, no 7Article in journal (Refereed)
    Abstract [en]

    Novel all-polyamide composite (APC) has been developed to replace traditional coated fabrics with good interfacial adhesionand enhanced recyclability. The composite is fully recyclable since it contains no other materials except polyamide. APC was preparedby partially dissolving a polyamide fabric by treatment with a film-forming polyamide solution. The effect of the polyamidesolution concentration and gelling time on tensile and viscoelastic properties of APCs was investigated to explore the optimum processingparameters for balancing the good interfacial adhesion. The composite properties were studied by dynamic mechanical thermalanalysis (DMTA), tensile testing and scanning electron microscopy (SEM). The results showed a good adhesion between the coatingand the fabric. A new method was introduced to convert a low value added textile waste to a high value-added product. The compositeis tunable, in terms of having a dense or a porous top-layer depending on the end-use requirements.

  • 35.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Vrignaud, Thomas
    Tissot, Clément
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical Recycling of PLA Filled with a High Level of Cellulose Fibres2016In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 25, no 3, p. 185-195Article in journal (Refereed)
    Abstract [en]

    Composites consisting of 30 vol% PLA and 70 vol% cellulose fibres were prepared with compression moulding. In the first part of the study, the recyclability of this composite material was investigated by grinding the material and using the recyclate obtained as a filler for PLA. Thus, the recyclate was compounded with PLA in loadings ranging from 20 to 50 wt%. The composites obtained were characterised by tensile tests, Charpy impact tests, DMTA, and SEM. Tests showed that the recyclate had a relatively good reinforcing effect. Stress at break increased from about 50 to 77 MPa and the modulus increased from 3.6 to 8.5 GPa. In the second part of the study, the ability to mechanically recycle the composites obtained was evaluated by repeated processing. Composite with two loadings of the recyclate (20 wt% and 50 %) was injection moulded repeatedly, six times. Tests showed that the composite material with 20 wt% recyclate could withstand six cycles relatively well, while the composite with the higher load degraded much more quickly. For the composites with 50 wt% recyclate, signs of polymer degradation could be seen already after reprocessing the composite once.

  • 36.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fazelinejad, Samaneh
    Skrifvars, Ville-Viktor
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical recycling of polylactic acid composites reinforced with wood fibres by multiple extrusion and hydrothermal ageing2016In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 35, no 16, p. 1248-1259Article in journal (Refereed)
  • 37.
    Hatamvand, Mohammad
    et al.
    Department of Textile Engineering, Yazd University, Yazd, Iran.
    Mirjalili, Seyed Abbas
    Department of Textile Engineering, Yazd University, Yazd, Iran.
    Fattahi, Saeid
    Department of Textile Engineering, Yazd University, Yazd, Iran.
    Bashir, Tariq
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    OPTIMUM DRAFTING CONDITIONS OF POLYESTER AND VISCOSE BLEND YARNS2016In: AUTEX Research Journal, ISSN 1470-9589, E-ISSN 2300-0929Article in journal (Refereed)
    Abstract [en]

    In this study, we used an experimental design to investigate the influence of the total draft, break draft, distancebetween the aprons (Clips) and production roller pressure on yarn quality in order to obtain optimum draftingconditions for polyester and viscose (PES/CV) blend yarns in ring spinning frame. We used PES fibers (1.4 dtex ×38 mm long) and CV fibers (1.6 dtex × 38 mm long) to spin a 20 Tex blend yarn of PES (70%)/CV (30%) blend ratio.When the break draft, adjustment of distance between of aprons and roller pressure is not reasonable, controllingand leading of the fibers is not sufficient for proper orientation of the fibers in the yarn structure to produce a highquality yarn. Experimental results and statistical analysis show that the best yarn quality will be obtained underdrafting conditions total draft of 38, 1.2 break draft, 2.8 mm distance between of aprons and maximum pressure ofthe production top roller.

  • 38.
    Mujica-Garcia, A
    et al.
    Dipartimento di Ingegneria Civile e Ambientale, Università di Perugia, Italy.
    Hoosmand, Saleh
    Division of Materials Science, Composite Centre Sweden, Luleå University of Technology, Luleå, Sweden .
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kenny, J M
    Dipartimento di Ingegneria Civile e Ambientale, Università di Perugia, Italy.
    Oksman, Kristiina
    Division of Materials Science, Composite Centre Sweden, Luleå University of Technology, Luleå, Sweden .
    Peponi, L
    Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Spain.
    Poly(lactic acid) melt-spun fibers reinforced with functionalized cellulose nanocrystals2016In: RSC Advances, E-ISSN 2046-2069, Vol. 6, p. 9221-9231Article in journal (Refereed)
    Abstract [en]

    Poly(lactic acid)-cellulose nanocrystals (PLA/CNC) nanocomposite fibers with 1% weight fraction of nanocrystals were prepared via melt-spinning. In order to improve the compatibility between PLA and the CNC, PLLA chains were grafted onto the CNC surface using a "grafting from" reaction. For comparison, melt-spun PLA fibers and nanocomposites with unmodified CNC were also prepared. The morphology and thermal and mechanical properties of the fibers with different draw ratios were determined. The results of this research show that the surface modification together with drawing resulted in improved fiber properties, which are expected to depend on the alignment of the CNC and PLA molecular chains. The modification is also expected to lead to a flexible interface, which leads to more stretchable fibers. The main conclusion is that PLLA grafting is a very promising approach to improve the dispersion of CNC in PLA, thus creating interfacial adhesion between the phases and making it possible to spin fibers that can be drawn with improved mechanical performance.

  • 39.
    Seoane, Fernando
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Soroudi, Azadeh
    University of Borås, Faculty of Textiles, Engineering and Business.
    Abtahi, Farhad
    KTH, Medicinsk teknik.
    Lu, Ke
    KTH-School of Technology and Health.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Printed Electronics Enabling a Textile-friendly Interconnection between Wearable Measurement Instrumentation & Sensorized Garments2016Conference paper (Refereed)
  • 40.
    Persson, Nils-Krister
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bashir, Tariq
    University of Borås, Faculty of Textiles, Engineering and Business.
    Brorström, Björn
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hedegård, Lars
    University of Borås, Faculty of Textiles, Engineering and Business.
    Carlson Ingdahl, Tina
    University of Borås, Faculty of Textiles, Engineering and Business.
    Larsson, Jonas
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lindberg, Ulla
    University of Borås, Faculty of Textiles, Engineering and Business.
    Löfström, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Oudhuis, Margaretha
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pal, Rudrajeet
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pettersson, Anita
    University of Borås, Faculty of Textiles, Engineering and Business.
    Påhlsson, Birgitta
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Worbin, Linda
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Re: en ny samhällssektor spirar2016Report (Other academic)
    Abstract [sv]

    Resurser och hållbarhet är nära förknippade. Hållbarhet innebär att hushålla med resurser - materiella, miljömässiga och mänskliga. Och hushållning är per definition kärnan i ekonomi. Man börjar alltmer se framväxten av en hel arsenal av verktyg och förhållnings- och angreppssätt för att bygga hållbarhet. Detta förenas av ett synsätt att det som hitintills setts  om avfall och värdelöst, och rent utav besvärligt att ta hand om, nu blir en värdefull resurs. Det glömda och gömda kommer åter. Faktum är att många ord och begrepp kring detta börjar på just åter- eller re- . Internationellt talar man om Redesign, Recycling, Remake, Recycle, Recraft, Reuse, Recreate, Reclaim, Reduce, Repair, Refashion.

    Vad är då allt detta? Ja, vill man dra det långt, är det inte mindre än framväxten av ett nyvunnet sätt att tänka, ja av en ny samhällssektor, en bransch och en industri,  sammanbundet av filosofin att återanvändningen, spillminskningen, vidarebruket, efterlivet anses som viktiga faktorer för ett miljömedvetet samhälle. Re: blir paraplytermen för detta. I denna antologi av forskare från skilda discipliner vid Högskolan i Borås lyfts ett antal av dessa begrepp inom Re: fram.

  • 41.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bourmaud, Alain
    Beaugrand, Johnny
    Le Duigou, Antoine
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baley, Christophe
    Recycling of L-Poly-(lactide)-Poly-(butylene-succinate)-flax biocomposite2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 128, p. 77-88Article in journal (Refereed)
    Abstract [en]

    The development of new plant fibre composites is a key point in the development of semi-structural biodegradable or biobased parts, especially for automotive applications. The aim of this original and innovating work is to study, at different scales, the recycling ability of a fully biodegradable L-Poly-(lactide)-Poly-(butylene-succinate)-flax (PLLA-PBS-flax) biocomposite. The biocomposites were manufactured by twin-screw extrusion followed by injection moulding, then the recycling behaviour was studied during successive injection moulding cycles. Firstly, we investigated the length of the flax fibre after compounding and injection, as well as the cell wall stiffness and hardness, by in-situ nanoindentation tests. Secondly, we focused on the effects of recycling on thermal, rheological and tensile properties. We highlighted a severe evolution of the cell wall properties, especially concerning the polysaccharidic matrix after the first thermal cycle, nanoindentation properties remaining quasi-stable after this first drop. Furthermore, the biocomposites did not show any significant evolution of their mechanical performances during cycle three or four of the first injection cycles; after this plateau, the tensile strength and strain as well as impact energy were significantly altered due to the conjugated fibre length decrease and degradation of the PLLA, the latter being emphasized when the flax fibre is embedded. Nevertheless, this fully biodegradable composite exhibits a suitable recycling behaviour for 3 or 4 cycles, which is sufficient for industrial applications.

  • 42.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fuchs, Torsten
    Stöss, Michael
    Root, Andrew
    MagSol, Helsinki, Finland.
    Stenvall, Erik
    Chalmers tekniska högskola.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Recycling of wood fiber-reinforced HDPE by multiple reprocessing2016In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, no 35Article in journal (Refereed)
    Abstract [en]

    The mechanical recycling of high-density polyethylene (HDPE) reinforced with wood fiber was studied by means of repeated injection moulding. The change in properties during the recycling was monitored by tensile and flexural tests, Charpy impact tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), FTIR spectroscopy, and by measuring the fiber lengths. Tests were also done where injection moulding was combined with subsequent accelerated thermo-oxidative ageing and thereafter repeated numerous times. The results showed that the HDPE composites were relatively stable toward both the ageing conditions and the repeated injection moulding. The change of the mechanical properties was mainly observed as an increased elongation at max. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43877. © 2016 Wiley Periodicals, Inc.

  • 43.
    Bakare, Fatimat O.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ramamoorthy, Sunil Kumar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Thermomechanical properties of bio-based composites made from a lactic acid thermoset resin and flax and flax/basalt fibre reinforcements2016In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, p. 176-184Article in journal (Refereed)
    Abstract [en]

    Low viscosity thermoset bio-based resin was synthesised from lactic acid, allyl alcohol and pentaerythritol. The resin was impregnated into cellulosic fibre reinforcement from flax and basalt and then compression moulded at elevated temperature to produce thermoset composites. The mechanical properties of composites were characterised by flexural, tensile and Charpy impact testing whereas the thermal properties were analysed by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results showed a decrease in mechanical properties with increase in fibre load after 40 wt.% for the neat flax composite due to insufficient fibre wetting and an increase in mechanical properties with increase fibre load up to 60 wt.% for the flax/basalt composite. The results of the ageing test showed that the mechanical properties of the composites deteriorate with ageing; however, the flax/basalt composite had better mechanical properties after ageing than the flax composite before ageing.

  • 44.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Persson, Anders
    University of Borås, Faculty of Textiles, Engineering and Business.
    A Review of Natural Fibers Used in Biocomposites: Plant, Animal and Regenerated Cellulose Fibers2015In: Polymer Reviews, ISSN 1558-3724, Vol. 55, no 1, p. 107-162Article in journal (Refereed)
    Abstract [en]

    Natural fibers today are a popular choice for applications in composite manufacturing. Based on the sustainability benefits, biofibers such as plant fibers are replacing synthetic fibers in composites. These fibers are used to manufacture several biocomposites. The chemical composition and properties of each of the fibers changes, which demands the detailed comparison of these fibers. The reinforcement potential of natural fibers and their properties have been described in numerous papers. Today, high performance biocomposites are produced from several years of research. Plant fibers, particularly bast and leaf, find applications in automotive industries. While most of the other fibers are explored in lab scales they have not yet found large-scale commercial applications. It is necessary to also consider other fibers such as ones made from seed (coir) and animals (chicken feather) as they are secondary or made from waste products. Few plant fibers such as bast fibers are often reviewed briefly but other plant and animal fibers are not discussed in detail. This review paper discusses all the six types of plant fibers such as bast, leaf, seed, straw, grass, and wood, together with animal fibers and regenerated cellulose fibers. Additionally, the review considers developments dealing with natural fibers and their composites. The fiber source, extraction, availability, type, composition, and mechanical properties are discussed. The advantages and disadvantages of using each biofiber are discussed. Three fabric architectures such as nonwoven, woven and knitted have been briefly discussed. Finally, the paper presents the overview of the results from the composites made from each fiber with suitable references for in-depth studies.

  • 45. Dural-Erem, Aysin
    et al.
    Erem, Hasan
    Ozcan, Gulay
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Anatase titanium dioxide loaded polylactide membranous films: preparation, characterization, and antibacterial activity assessment2015In: Journal of the Textile Institute, ISSN 0040-5000, E-ISSN 1754-2340, Vol. 106, no 6Article in journal (Refereed)
    Abstract [en]

    In this study, the preparation method and characteristics of anatase titanium dioxide (TiO2) nanoparticle-loaded polylactide (PLA) films and their antibacterial efficacy against Klebsiella pneumoniae (ATCC 4352) and Staphylococcus aureus (ATCC 6538) bacterium were studied. A series of PLA nanocomposites containing, respectively, 0, 1, and 5% (wt.) titanium dioxide (TiO2) nanoparticles were prepared by melt intercalation method. The effect of TiO2 nanoparticles on the thermal and mechanical characteristics of the films was determined. Thermal analysis showed that the glass transition temperature, crystallization temperature, melting temperature, and decomposition temperatures (Td0.5 and Td0.05) decreased with the filler content. The results obtained from tensile tests showed that TiO2 nanoparticles reduced the mechanical properties and moduli of the PLA films. On the other hand, the water absorption properties of the nanocomposite films increased with the addition of nanoparticles and nanocomposite films exhibited bacteriostatic and limited bactericidal efficacy according to AATCC 147. Consequently, nanocomposite films may be good materials for medical applications due to their membranous properties.

  • 46.
    Baghaei, Behnaz
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Characterization of thermoplastic natural fibre composites made from woven hybrid yarn prepregs with different weave pattern2015In: Composites Part A: Applied Science and Manufacturing, Vol. 81, no February 2016, p. 139-144Article in journal (Other academic)
  • 47.
    Baghaei, Behnaz
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Investigation of pattern style of woven fabrics produced from hybrid wrap spun yarns on fabricated composite2015Conference paper (Other academic)
  • 48.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical and thermal properties of the textile bio-composites: measurement and prediction2015In: , 2015Conference paper (Refereed)
  • 49.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Esmaeili, Nima
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Afshar, Shahrzad
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical properties for bio-based thermoset composites made from lactic acid, glycerol and viscose fibers2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 603-613Article in journal (Refereed)
  • 50.
    Kalantar Mehrjerdi, Adib
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Tariq, Bashir
    University of Borås, Faculty of Textiles, Engineering and Business.
    Melt Flow and Rheological Properties of Talc-Polyethylene Compounds2015Conference paper (Refereed)
  • 51.
    Lund, Anja
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Melvinsson, Rebecca
    Malm, Veronica
    University of Borås, Faculty of Textiles, Engineering and Business.
    Wand, Charlie
    The University of Manchester · School of Chemical Engineering and Analytical Science.
    Tahir, Mohammad Waseem
    Högskolan i Skövde.
    Skrifvars, Mikael
    Stigh, Ulf
    Högskolan i Skövde.
    Bolton, Kim
    University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Melt Spun PVDF Actuator Fibres: the Effect of Spin-Line Orientation and MW on Actuation2015In: Regional Conference Polymer Processing Society Graz 2015: Book of Abstracts, 2015, p. 306-Conference paper (Other academic)
    Abstract [en]

    This paper presents the melt spinning and characterisation of polymer actuator fibres; fibres that reversibly contract along the fibre axis in response to heat. Recently, Haines et al (1) showed that low-cost filaments, e.g. fishing lines, can be relevant precursors for artificial muscles. They demonstrated a reversible fibre-direction thermal contraction, which was significantly amplified when the fibres were twisted and coiled. The effect was explained to result from an increase in the conformational entropy of the amorphous phase. In earlier studies on negative thermal expansion in anisotropic polymer structures, it has been shown that the negative thermal expansion in oriented highly crystalline polymers approaches values typical of polymer crystals (2).

     

    To further investigate the mechanisms behind these seemingly simple artificial muscles, we have melt spun fibres from poly(vinylidene fluoride) (PVDF) – Solef  1006 and 1008 kindly provided by Solvay (Milan, Italy) – and compared their properties to a commercially available PVDF-fishing line. The fibres were characterised with respect to their thermal actuation properties, crystal morphology and degree of orientation along the spin-line axis.

     

    We have further done modelling on the molecular and macroscopic levels examining the possible mechanisms of negative thermal expansion in semi-crystalline PVDF. We believe that tie molecules (a polymer chain linking two crystalline regions) are the predominant factor influencing actuation. Two mechanisms are considered: an entropic effect and a conformational change effect. The entropic effect causes an increase in the elastic stiffness with an increase in temperature, effectively resulting in a contraction of a strained fibre. The conformational change effect is also expected to contribute to contraction as tie molecules, under strain, revert to their unloaded preferred conformation when heated.

    1. C. S. Haines et al., Artificial Muscles from Fishing Line and Sewing Thread. Science 343, 868-872 (2014).
    2. C. L. Choy et al., Negative Thermal Expansion in Oriented Crystalline Polymers. Journal of Polymer Science: Polymer Physics Edition 19, 335-352 (1981).
  • 52.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajan, Rathish
    Technology Centre Ketek Ltd.
    Rahkonen, Mirva
    Technology Centre Ketek Ltd.
    Rainosalo, Egidija
    Technology Centre Ketek Ltd.
    Modification of epoxy resin and its influence on tensile properties of viscose fabric composite2015In: ICCM20 Programme and book of abstracts, 2015Conference paper (Refereed)
  • 53.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ansari, Farhan
    Berglund, Lars
    Nanostructured biocomposites based on unsaturated polyester resin and a cellulose nanofiber network2015In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 117, p. 298-306Article in journal (Refereed)
  • 54.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Natural fibres for structural composites - concepts and opportunities2015Conference paper (Other academic)
  • 55.
    Jabbari, Mostafa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Novel lightweight and highly thermally insulative silica aerogel-doped poly (vinyl chloride)-coated fabric composite2015In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 34, no 19, p. 1581-1592Article in journal (Refereed)
    Abstract [en]

    Novel lightweight and highly thermal insulative aerogel-doped poly(vinyl chloride)-coated fabric composites wereprepared on woven fabrics made of polyester fibres using knife coating method, and their performances were comparedwith neat composite. The composites were prepared by incorporating a commercial aerogel to a ‘green’ poly(vinylchloride) (PVC) plastisol. The effect of aerogel-content, thermal insulating property, thermal degradation, surface characteristics,tensile and physical properties of the composites were investigated. Results revealed that aerogel couldreduce thermal conductivity, density and hydrophilicity of the composites dramatically without significant decrease inother properties. Experimental results showed that thermal insulation properties were enhanced by 26% (from 205 to152 mW/m-K), density decreased by 17% (from 1.132 to 0.941 g/cm3) and hydrophobicity increased by 16.4% (from76.02 to 88.671.48) with respect to the unmodified coated fabric. Analyses proved that composite with 3% aerogel isthe lightest by weight, while 4% showed the highest thermal insulation. The results showed that 4% is the criticalpercentage, and preparation of composites with aerogel content higher than 4% has limitations with the given formulationdue to high viscosity of plastisol. The prepared composite has potential applications in many fields such asdevelopment of textile bioreactors for ethanol/biogas production from waste materials, temporary houses and tents,facade coverings, container linings and tarpaulins. The prepared composite can be considered ‘green’ due to usage of anon-phthalate environment-friendly plasticiser.

  • 56.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat
    University of Borås, Faculty of Textiles, Engineering and Business.
    Herrmann, Rene
    Arcada University of Applied Science.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    The effect of surface treatments, silane and alkali, on regenerated cellulose fibers was studied by using the treated fibers as reinforcement in lactic acid thermoset bioresin. The surface treatments were performed to improve the physico–chemical interactions at the fiber–matrix interface. Tensile, flexural and impact tests were used as indicator of the improvement of the interfacial strength. Furthermore, thermal conductivity, viscoelasticity measurements as well as microscopy images were made to characterize the fiber surface treatments and the effect on adhesion to the matrix. The results showed that silane treatment improved the mechanical properties of the composites as the silane molecule acts as link between the cellulose fiber and the resin (the fiber bonds with siloxane bridge while the resin bonds with organofunctional group of the bi-functional silane molecule) which gives molecular continuity in the interphase of the composite. Porosity volume decreased significantly on silane treatment due to improved interface and interlocking between fiber and matrix. Decrease in water absorption and increase in contact angle confirmed the change in the hydrophilicity of the composites. The storage modulus increased when the reinforcements were treated with silane whereas the damping intensity decreased for the same composites indicating a better adhesion between fiber and matrix on silane treatment. Thermogravimetric analysis indicated that the thermal stability of the reinforcement altered after treatments. The resin curing was followed using differential scanning calorimetry and the necessity for post-curing was recommended. Finite element analysis was used to predict the thermal behavior of the composites and a non-destructive resonance analysis was performed to ratify the modulus obtained from tensile testing. The changes were also seen on composites reinforced with alkali treated fiber. Microscopy images confirmed the good adhesion between the silane treated fibers and the resin at the interface.

  • 57.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Adekunle, Kayode
    Processing of Lyocell fiber mat: An alternative renewable reinforcement in composite manufacturing2015In: Green and Sustainable Chemistry, ISSN 2160-6951, E-ISSN 2160-696X, Vol. 5, no 2, p. 47-54Article in journal (Refereed)
    Abstract [en]

    The carding of the Lyocell cellulose fiber was done with a cylindrical cross lap machine supplied by Cormatex Prato, Italy. Several mats were made by carding and needle punching in order to have a compact and well entangled mat suitable for reinforcement. The speed of the cross lap machine, the frequency of needle punching, the number of times the mat goes through needle punching, the feeding rate of the carded fiber and the depth of needle penetration determined the level of entanglement of the Lyocell fiber which ultimately increased the mechanical properties of the fiber. The good mechanical properties of the carded Lyocell fiber made it a renewable and environmentally friendly alternative as reinforcement in composite manufacturing. Compared with other jute fiber reinforced composites, the mechanical properties of the resulting Lyocell composites were found to be better. Regenerated cellulose fiber (Lyocell) composites were environmentally friendly and the mechanical properties were comparable to those of natural fibers.

  • 58.
    Mylläri, Ville
    et al.
    Tampere University of Technology.
    Fatarella, Enrico
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Ruzzante, Marco
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Pogni, Rebecca
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Barratto, Maria
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjälä, Seppo
    Tampere University of Technology.
    Järvelä, Pentti
    Tampere University of Technology.
    Production of sulfonated polyetheretherketone/polypropylene fibers for photoactive textiles2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 39Article in journal (Refereed)
    Abstract [en]

    New photocatalytic fibers made of sulfonated polyetheretherketone (SPEEK)/polypropylene (PP) are melt compounded and melt spun, first on laboratory scale and then on a semi-industrial scale. Fiber spinnability is optimized and the fibers are characterized using mechanical testing, electron paramagnetic resonance (EPR) spectroscopy, and scanning electron microscopy (SEM). According to the results, the fiber spinnability remains at a good level up to 10 wt % SPEEK concentration. Optimal processing temperature is 200°C due to the thermal degradation at higher temperatures. EPR measurements show good and long-lasting photoactivity after the initial irradiation but also decay in the radical intensity during several irradiation cycles. Mechanical tenacity of the SPEEK/PP 5:95 fiber is approximately 20% lower than for otherwise similar PP fiber. The fiber is a potential alternative to compete against TiO2-based products but more research needs to be done to verify the real-life performance.

  • 59.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mabille, Colinne
    University of Borås, Faculty of Textiles, Engineering and Business.
    Wojno, Sylvia
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dhakal, Hom
    University of Portsmouth.
    Zhang, Zhongyi
    University of Portsmouth.
    Resin transfer moulding processing of biocomposites from warp knitted and carded cellulose reinforcements2015Conference paper (Refereed)
  • 60.
    Fatarella, Enrico
    et al.
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Mylläri, Ville
    Tampere University of Technology.
    Ruzzante, Marco
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Pogni, Rebecca
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Baratto, Maria
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjälä, Seppo
    Tampere University of Technology.
    Järvelä, Pentti
    Tampere University of Technology.
    Sulfonated polyetheretherketone/polypropylene polymer blends for the production of photoactive materials2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 8Article in journal (Refereed)
  • 61.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bashir, Tariq
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ingman, Petri
    University of Turku.
    Srivastava, Rajiv
    Indian Institute of Technology Delhi.
    Synthesis and characterisation of unsaturated lactic acid based thermoset bio-resins2015In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, no June 2015, p. 570-582Article in journal (Refereed)
  • 62.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mabille, Coline
    Wojno, Sylwia
    Zhang, Zhongyi
    University of Portsmouth.
    Dhakal, Hom
    University of Portsmouth.
    Warp knitted and carded regenerated cellulose reinforced biocomposites2015Conference paper (Other academic)
  • 63.
    Baghaei, Behnaz
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Masoud, Salehi
    University of Borås, School of Engineering.
    Aligned hemp yarn reinforced biocomposites: porosity, water absorption, thermal and mechanical properties2014Conference paper (Refereed)
  • 64. Hooshmand, Saleh
    et al.
    Aitomäki, Yvonne
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mathew, Ali
    Oksman, Kristiina
    All-cellulose nanocomposite fibers produced by melt spinning cellulose acetate butyrate and cellulose nanocrystals2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 21, no 4, p. 2665-2678Article in journal (Refereed)
    Abstract [en]

    Bio-based continuous fibers were prepared by melt spinning cellulose acetate butyrate (CAB), cellulose nanocrystals (CNC) and triethyl citrate. A CNC organo-gel dispersion technique was used and the prepared materials (2 and 10 wt% CNC) were melt spun using a twin-screw micro-compounder and drawn to a ratio of 1.5. The microscopy studies showed that the addition of CNC in CAB resulted in defect-free and smooth fiber surfaces. An addition of 10 wt% CNC enhanced the storage modulus and increased the tensile strength and Young’s modulus. Fiber drawing improved the mechanical properties further. In addition, a micromechanical model of the composite material was used to estimate the stiffness and showed that theoretical values were exceeded for the lower concentration of CNC but not reached for the higher concentration. In conclusion, this dispersion technique combined with melt spinning can be used to produce all-cellulose nanocomposites fibers and that both the increase in CNC volume fraction and the fiber drawing increased the mechanical performance.

  • 65. Arshad, Khubaib
    et al.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Vivod, Vera
    Valh, Julija
    Voncina, Bojana
    Biodegradation of natural textile materials in soil2014In: Tekstilec, ISSN 0351-3386, Vol. 57, no 2, p. 118-132Article in journal (Refereed)
    Abstract [en]

    World is facing numerous environmental challenges, one of them being the increasing pollution both in the atmosphere and landfi lls. After the goods have been used, they are either buried or burnt. Both ways of disposal are detrimental and hazardous to the environment. The term biodegradation is becoming more and more important, as it converts materials into water, carbon dioxide and biomass, which present no harm to the environment. Nowadays, a lot of research is performed on the development of biodegradable polymers, which can “vanish” from the Earth surface after being used. In this respect, this research work was conducted in order to study the biodegradation phenomenon of cellulosic and non-cellulosic textile materials when buried in soil, for them to be used in our daily lives with maximum effi ciency and after their use, to be disposed of easily with no harmful eff ects to the environment. This research indicates the time span of the use life of various cellulosic and non-cellulosic materials such as cotton, jute, linen, fl ax, wool when used for the reinforcement of soil. The visual observations and applied microscopic methods revealed that the biodegradation of cellulose textile materials proceeded in a similar way as for non-cellulosic materials, the only difference being the time of biodegradation. The non-cellulosic textile material (wool) was relatively more resistant to microorganisms due to its molecular structure and surface. Keywords: biodegradation, composting, natural textile materials, FT-IR

  • 66.
    Barghi, Hamidreza
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Catalytic Synthesis of Bulk Hydrophilic Acetaldehyde-Modified Polyamide 462014In: Current Organic Synthesis, ISSN 1570-1794, E-ISSN 1875-6271, Vol. 11, no 6, p. 288-294Article in journal (Refereed)
    Abstract [en]

    Hydrophilization of Polyamide 46 (PA46) via modification with acetaldehyde in continuous phase was studied. The chemical modification of PA 46 with acetaldehyde resulted in a water-swollen polymer with hydrophilic property. The polyamide 46 undergoes a nucleophilic addition with acetaldehyde in the presence of aluminum chloride as a catalyst. The extent of bulk hydroxyethylation using AlCl3 resulted in 95.65% modification counted as total N-hydroxyethylated polyamide 46. The modification resulted in improved hydrophilic properties, and a maximum surface free energy of 44.6 mJ/m2 was achieved after 3 h reaction, whereas the unmodified PA46 had a surface free energy of 11.2 mJ/m2. In addition, thermal properties of the polymers were studied using differential scanning calorimetry and thermogravimetric analyses. The functionalization leads to decrease in the crystallization energy from 88 J/g to 51 J/g, while the melting energy is changed from 110 J/g to 53 J/g. Furthermore, the thermal stability of the PA46 to pyrolysis was diminished after hydroxylation.

  • 67.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Development of functional fibres for textiles and composites2014Conference paper (Other academic)
  • 68.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Rissanen, Marja
    Effect of alkali and silane surface treatments on regenerated cellulose fibre type (Lyocell) intended for composites2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1Article in journal (Refereed)
    Abstract [en]

    Cellulose fibres have significant importance and potential for polymer reinforcement. It is essential to modify the surface of the fibre to obtain good fibre-matrix interface. Surface treatments can increase surface roughness of the fibre, change its chemical composition and introduce new moieties that can effectively interlock with the matrix, resulting in good mechanical properties in the composites. This is mainly due to improved fibre-matrix adhesion. The treatments may also reduce the water absorption rate by converting part of the hydroxyl groups on the fibre surface into other functional groups. Chemical modification of the surface of a regenerated cellulose fibre of the Lyocell type was carried out by alkali and silane treatments, which significantly changed the properties of the Lyocell fibres. Three parameters were considered when the fibre surface treatment was done: concentration (2–15 wt%), temperature (25 and 50 C) and time (30 min–72 h). Fourier transform infrared spectroscopy and Raman spectroscopy were used for chemical analysis and qualitative analysis of the cellulose crystallinity due to the surface treatments; subsequently, mechanical strength of the fibres was tested by tensile testing. Weight loss, moisture regain and swelling measurements were taken before and after treatments, which showed the obvious changes in fibre properties on treatment. Heat capacity of the fibres was measured for untreated and treated fibres, and thermal degradation of fibres was examined to see the stability of fibres at elevated temperatures. Wettability and surface energies were measured using dynamic contact angle method in three wetting mediums. Scanning electron microscopy was used to study the morphological properties of the fibres.

  • 69. Persson, Maria
    et al.
    Lorite, Gabriela
    Kokkonen, Hanna
    Lehenkari, Petri
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Tuukkanen, Juha
    Effect of bioactive extruded PLA/HA composite films on focal adhesion formation of preosteoblastic cells2014In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 121, p. 409-416Article in journal (Refereed)
    Abstract [en]

    The quality of the initial cell attachment to a biomaterial will influence any further cell function, including spreading, proliferation, differentiation and viability. Cell attachment is influenced by the material's ability to adsorb proteins, which is related to the surface chemistry and topography of the material. In this study, we incorporated hydroxyapatite (HA) particles into a poly(lactic acid) (PLA) composite and evaluated the surface structure and the effects of HA density on the initial cell attachment in vitro of murine calvarial preosteoblasts (MC3T3-EI). Scanning electron microscopy (SEM), atomic force microscopy (AFM) and infrared spectroscopy (FTIR) showed that the HA particles were successfully incorporated into the PLA matrix and located at the surface which is of importance in order to maintain the bioactive effect of the HA particles. SEM and AFM investigation revealed that the HA density (particles/area) as well as surface roughness increased with HA loading concentration (i.e. 5, 10, 15 and 20wt%), which promoted protein adsorption. Furthermore, the presence of HA on the surface enhanced cell spreading, increased the formation of actin stress fibers and significantly improved the expression of vinculin in MC3T3-E1 cells which is a key player in the regulation of cell adhesion. These results suggest the potential utility of PLA/HA composites as biomaterials for use as a bone substitute material and in tissue engineering applications.

  • 70. Rajan, Rathish
    et al.
    Riihivuori, Johanna
    Rainosalo, Egidija
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Järvelä, Pentti
    Effect of viscose fabric modification on the mechanical and water absorption properties of composites prepared through vacuum infusion2014In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 33, no 15, p. 1416-1429Article in journal (Refereed)
    Abstract [en]

    Viscose fabric-reinforced unsaturated polyester composites were successfully prepared through vacuum infusion process. Unidirectional viscose fabric was modified by two different organosilane coupling agents and by acetylation treatment. The main objective was to study the influence of fabric treatment on the mechanical and water absorption properties of the composites. Flexural, tensile and impact properties of composites were studied. The results from mechanical testing of composites pointed out that 3-aminopropyltriethoxy silane treatment increased the flexural and impact strengths of the composites with respect to untreated fabric composite. The impact strength of 3-aminopropyltriethoxy silane-treated fabric composites almost doubled compared to the value of untreated fabric composite. Among all the composites under study, those with fabrics treated by 2 vol% 3-aminopropyltriethoxy silane in ethanol/water (95:5) solution exhibited significant improvement in water uptake resistance. An unsaturated polyester gelcoat and topcoat were applied as the outer surface on the composites with untreated fabric. This was done in order to investigate the visual surface appearance and evaluate the gelcoat and topcoat effect on water absorption after accelerated water immersion test. The regenerated cellulose fibre as reinforcement shows high potential to be used as an alternative for natural bast fibres, especially, when toughness of material matters. Chemical treatment of regenerated cellulose fibres could result in improvement in properties of polymer composites, considering that the appropriate treatment method is selected for the corresponding fibre–matrix system.

  • 71. Kalantar Mehrjerdi, Adib
    et al.
    Abebe Mengistu, Bemnet
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Effects of a titanate coupling agent on the mechanical and thermo-physical properties of talc-reinforced polyethylene compounds2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 13, p. 40449-40449Article in journal (Refereed)
    Abstract [en]

    An experimental study was carried out to investigate the effects of a titanate coupling agent on the mechanical properties, moisture absorption, and thermal conductivity of talc-filled high-density polyethylene (HDPE). Talc (0–35 wt %) was used as reinforcement particulate filler in an HDPE matrix and samples were prepared in a micro-compounder and an injection molding machine. Isopropyl tri(dioctyl)phosphate titanate (0.5 wt %) was used as coupling agent. Composites with and without coupling agent were evaluated for changes in mechanical and thermo-physical properties, morphology, and void content. Addition of the titanate coupling agent most often resulted in an increase in stiffness and tensile strength. Furthermore, both the void content and the elongation at break of composites were reduced. Results also showed that the coupling agent had no effects on the thermal conductivity, thermal diffusivity, and specific heat capacity of the composites. In addition, it was observed that the coupling agent was more effective at low concentrations of filler. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40449.

  • 72. Lee, Tae-Hyung
    et al.
    Jeon, Sera
    Kim, Hyun-Joong
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Evaluation of mechanical properties and interfacial adhesion of PLA/Lyocell composite with silane coupling agent2014Conference paper (Other academic)
  • 73. Dhakal, Hom N
    et al.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Zhang, Z Y
    Falling weight impact response of jute/methacrylated soybean oil bio-composites under low velocity impact loading2014In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 92, p. 134-141Article in journal (Refereed)
    Abstract [en]

    In this study, impact performance of bio-composites fabricated from jute/methacrylated soybean oil (MSO) subjected to low-velocity impact loading is presented. The composite laminates were fabricated using compression moulding technique and their thickness and weave architectures effect on the impact response were investigated and the experimental observations are reported. From the results obtained, it was observed that fibre orientation and thickness variation have a significant influence on the impact resistance of jute/MSO composite material. The results show that the total absorbed energy and maximum peak load increase linearly with an increase in the thickness. Among the composite samples investigated where thickness comprised of: 1, 1.5, 2, 2.5 and 3 mm, a composite reinforced with 46 yarns per 10 cm weft and 50 warp (W2-3 mm thick) is found to have highest resistance to impact damage compared to 32 and 15 yarn per 10 cm weft samples. This was attributed to the improved fibre/matrix interface as a result of surface treatment of jute fibres and the fibre architectures effect which create the cross-over points which act as stress distributors.

  • 74. Kalantar Mehrjerdi, Adib
    et al.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Geothermal pipe collector2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A geothermal pipe collector is provided. The geothermal pipe collector is made from a polymer composition comprising: more than 50wt% polyethylene, 0.1wt% -35wt% talc and 0.5wt% -10wt% carbon black.

  • 75.
    Baghaei, Behnaz
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Hybrid natural fibre reinforcements and prepregs for thermoplastic composites with improved performance and properties2014Conference paper (Other academic)
  • 76. Rajan, Rathish
    et al.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Järvelä, Pentti
    Lactic acid polymers: synthesis, properties & applications2014In: Handbook of Green Materials, Vol. 5. Biobased composite materials: their processing, properties and industrial applications / [ed] Kristiina Oksman, Aji P. Mathew, Alexander Bismarck, Orlando Rojas, Mohini Sain, World Scientific Publishing , 2014, p. 49-66Chapter in book (Refereed)
  • 77.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rissanen, Marja
    Tampere University of Technology.
    Ramamoorthy, Sunil Kumar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical and thermal characterization of compression moulded polylactic acid natural fiber composites reinforced with hemp and Lyocell fibers2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 15Article in journal (Refereed)
  • 78. Esmaeli, Nima
    et al.
    Bakare, Fatimat Oluwatoyin
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Afshar, Shahrzad Javanshir
    Åkesson, Dan
    University of Borås, School of Engineering.
    Mechanical properties for bio-based thermoset composites made from lactic acid, glycerol and viscose fibers2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 603-613Article in journal (Refereed)
    Abstract [en]

    Regenerated cellulose fibers were used to produce thermoset composites from a bio-based thermoset resin synthesized from lactic acid and glycerol. The resin was impregnated into the regenerated cellulose fiber and compression molded at elevated temperature to produce thermoset composites. Different fiber alignments (unidirectional and bidirectional), different reinforcement type (warp-knitted and non-woven) and varying fiber loading (65, 70 and 75 wt%) were investigated. The composites were characterized by flexural, tensile and Charpy impact testing and by dynamical mechanical thermal analysis. Water uptake and ageing properties in climate chamber were also characterized for the composites. The results showed that the composites had good mechanical properties. They can be produced with up to 70 wt% fiber content when using unidirectional (UD) and bidirectional fiber (BD) alignment, and with up to 65 wt% fiber content when using the non-woven (NW) reinforcement. The tensile modulus ranged between 11 and 14 GPa for UD composites, 7 and 8.5 GPa for BD composites and 5 and 7.5 GPa for NW composites. The flexural modulus ranged between 10 and 11.5 GPa for UD composites, 5 and 6.5 GPa for BD composites and 5 and 6 GPa for NW composites. The impact strength ranged between 130 and 150 kJ/m2 for UD composites, 98 and 110 kJ/m2 for BD composites and 17 and 20 kJ/m2 for NW composites. The result of the ageing test showed that the mechanical properties of the composites deteriorate with ageing but the addition of styrene somewhat counteracts the degradation, making the composite applicable for indoor use.

  • 79.
    Fazelinejad, Samaneh
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical Recycling of Polylactic Acid Reinforced with Calcium Carbonate2014Conference paper (Other academic)
    Abstract [en]

    Biopolymers are becoming increasingly popular and may help reduce oil dependency. As a result, industries’ attentions have been directed towards polylactic acid (PLA) which combines the advantages of being renewable and biodegradable resources at the same time. The upward trend of the bioplastics and biocomposites usage among consumers could have great consequence for the recycled plastics industry in the next few decades. While the mechanical recycling of many of the traditional, petro-based polymers have been studied in detail, bio-based polymers still need to be better characterized. The mechanical recycling of neat PLA has previously studied and tests show that it is possible to process PLA several times without significant loss of mechanical properties. However, commercial plastics are often used with some kind of filler. Due to the low production cost of chalk (mainly consisting of CaCO3) it is often added to commercial polymers. PLA can be filled with chalk and other fillers in order to improve the toughness and lowering the cost. The purpose of this project was to investigate the mechanical recycling of PLA compounded with chalk. PLA was compounded with 30 wt-% chalk and 5 wt-% plasticizer using a twin screw extruder. The mechanical recycling was simulated by multiple extrusion. Samples for mechanical testing were prepared by compress molding. The prepared compound was recycled up to 6 times by multiple extrusion. The mechanical and thermal properties were characterized after each cycle by TGA, DSC, DMTA, FTIR and tensile tests.

  • 80.
    Åkesson, Dan
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical recycling of polylactic acid reinforced with cellulose fibres2014Conference paper (Refereed)
    Abstract [en]

    The increased environmental awareness has drawn researchers’ attention to bio-based polymers and several polymers such as polylactic acid (PLA), Mater-bi and polyhydroxyalkanoates (PHA) have been studied extensively. It is not easy to replace conventional petro-based polymers and it is therefore likely that both petro- and bio-based polymers will coexists for a long time. The usage of bio-based polymers is however growing and this may have implications for the plastic recycling industry. The recycling of petro-based polymers is relatively well studied and, where it is cost effective, conventional, petro-based polymers are being recycled in the industry. However, the recycling of bio-based plastics and composites needs to be studied more in detail. While several bio-based polymers can be biologically degraded, it is of interest to study the mechanical recycling of these polymers. In order to minimize the energy usage and the consumption of renewable materials mechanical recycling can be a good option. PLA is an attractive polymer as it is both biodegradable and prepared from renewable materials. This polymer has received a lot of attention and several reviews have been written. Research has shown that neat PLA can be reprocessed several times without significant loss of mechanical properties. Biocomposites based on PLA reinforced with natural fibres have been studied extensively in the literature and there can be many industrial applications of these biocomposites, such as automotive components and materials for construction applications. However, the mechanical recycling of biocomposites is not well studied. Most studies in the literature concerns the recycling of polymers reinforced with wood flour. DuraPulp is a commercial quality consisting PLA fibres mixed with cellulose fibres. This biocomposite material can be processed with for example compression moulding. Adding cellulose fibres to the polymer matrix may significantly change how the material can be recycled. The purpose of this study was to study the mechanical recycling of this material. Sheets were first prepared from Durapulp. The sheets were then compression moulded, grinded and reprocessed again with compression moulding. The mechanical and thermal properties were characterized after each cycle. The feasibility to recycle Durapulp mechanically will be discussed.

  • 81. Hooshmand, Saleh
    et al.
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mathew, Ali
    Oksman, Kristiina
    Melt spun cellulose nanocomposite fibres: Comparison of two dispersion techniques2014In: Plastics, rubber and composites, ISSN 1465-8011, E-ISSN 1743-2898, Vol. 43, no 1, p. 15-24Article in journal (Refereed)
    Abstract [en]

    Biobased fibres of cellulose acetate butyrate (CAB) and cellulose nanocrystals (CNC) and triethyl citrate (TEC) as plasticiser were prepared by melt spinning. To obtain homogeneous dispersion of CNC, two different dispersion techniques were studied. In the first, the water content of the CNC suspension was reduced and exchanged to ethanol using centrifugation. In the second, the water in the CNC suspension was completely exchanged to ethanol by sol–gel process. Results showed that tensile modulus and tensile strength of the nanocomposite fibres produced with the first technique were lower than CAB–TEC fibres, but the fibres produced by the sol–gel process showed an increase in the tensile modulus and had no decrease in the strength. Optical microscopy of the fibres indicated a few aggregations on the sol–gel prepared materials. The results indicate that the sol–gel process is enhancing the dispersion of CNC and can be a suitable way to prepare nanocomposite fibres.

  • 82.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Wang, Yanfei
    Afshar, Shahrzad Javanshir
    Esmaeli, Nima
    Åkesson, Dan
    University of Borås, School of Engineering.
    Morphological and mechanical properties of a biobased composite from a lactic acid based thermoset resin and viscose fiber reinforcement2014Conference paper (Refereed)
  • 83.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Natural fibers for structural composite applications: concepts and opportunities2014Conference paper (Refereed)
  • 84.
    Baghaei, Behnaz
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Salehi, Masoud
    Bashir, Tariq
    University of Borås, School of Engineering.
    Rissanen, Marja
    Nousiainen, Pertti
    Novel aligned hemp fibre reinforcement for structural biocomposites: Porosity, water absorption, mechanical performances and viscoelastic behaviour2014In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 61, p. 1-12Article in journal (Refereed)
    Abstract [en]

    This paper examines the thermal and mechanical behaviour as well as moisture absorption of aligned hemp composites using hemp/PLA wrap spun yarns. Uniaxial composites were fabricated with 30 mass% hemp using compression moulding. The properties of composites in terms of hemp fibre orientation (aligned and random), off-axis angle and alkali treatment were investigated. It was found that the testing direction influenced the mechanical properties of the composites. Compared with all the fabricated composites, the aligned alkali hemp/PLA yarn composite possessed the best mechanical properties, including tensile, flexural and impact strengths, lower porosity and water absorption. The water absorption for all composites was higher than for neat PLA, both at room temperature and 80 C. The PLA in its treated composites had higher crystallinity, which was attributed to effective heterogeneous nucleation induced by hemp. Based on SEM observation and theoretical analysis of DMTA data, there was a favourable interfacial adhesion in all composites.

  • 85.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, School of Engineering.
    Kundu, Chanchal Kumar
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Bashir, Tariq
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Properties of green composites with regenerated cellulose fiber and soybean-based thermoset for technical applications2014In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 33, no 2, p. 193-201Article in journal (Refereed)
    Abstract [en]

    Composites were developed by reinforcing available non-woven Lyocell and viscose in acrylated epoxidized soybean oil (AESO). Compression molding was used to make composites with 40–60 wt% fiber content. The fiber content comprises only Lyocell or viscose fiber, or mixture of these fibers in known ratio. Hybrid composites were made by a mixture of both the fibers in known ratio and it affects the properties. The effect of hybridization was evident in most tests which gives us an opportunity to tailor the properties according to requirement. Lyocell fiber reinforced composites with 60 wt% fiber content had a tensile strength and modulus of about 135 MPa and 17 GPa, respectively. Dynamic mechanical analysis showed that the Lyocell fiber reinforced composites had good viscoelastic properties. The viscose fiber reinforced composites had the high percentage elongation and also showed relatively good impact strength and flexural modulus. Good fiber-matrix adhesion reflected in mechanical properties. SEM images were made to see the fiber-matrix compatibility.

  • 86. Fazelinejad, Samaneh
    et al.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Recycling of Poly Lactic Acid Reinforced with Calcium Carbonate by Multiple Processing2014Conference paper (Other academic)
    Abstract [en]

    The upward trend of the bioplastics and biocomposites usage among consumers could have great consequence for the recycled plastics industry in the next few decades. As a result,industries’ attentions have been directed towards Poly Lactic Acid (PLA) which combines the advantages of renewable and biodegradable resources at the same time. Since PLA is more environmentally friendly compared to traditional petroleum-based commodity polymers, it has benefited from an upturned trend of interest in different markets, like the packaging, textile, and automotive industries. However, it is not applicable in many fields due to its inherent brittleness; even though it is very beneficial as the result of high strength and high modulus. Due to the low production cost of Nano calcium carbonate (nano-CaCO3) (NCC) which is useful to improve the toughness of PLA, it has reached a wide market in such industries as plastics, paints, and inks. By adding Nano calcium carbonate to polymer, thermal,crystallization, mechanical, biodegradability and melt rheological properties will be improved. The mechanical recycling of neat PLA has previously studied as well as some research on blend PLA/NCC by Sabzi et al. However, the purpose of this project is to investigate the characterization of PLA blend with Chalk (CaCo3) and Plasticizer by focusing on thermaland mechanical properties. The filler, which is 30% calcium carbonate, and 5% plasticizer compound with PLA in a two screws extruder. Plasticizer is added to composite to make it softer and it is consider constant in all samples. Multiple extrusions and compress molding are methods which can help in studying the recyclability of polymeric materials containing bioplastic and its derivatives and in figuring out the stability or service life respectively. In addition, these methods make it possible to determine the impacts of thermal and thermo mechanical degradation. Bio composite was recycled up to 6 times by using extruder equipment and crushing. The mechanical and thermal properties were characterized after each cycle by TGA, DSC,DMTA, FTIR, tensile machine and flexural test. The study represents that by introducing 30% calcium carbonate to PLA, it can be recycled up to 6 times without meeting any significant change in the mechanical and thermal properties.

  • 87. Cho, Sung-Woo
    et al.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Hemanathan, Kumar
    Mahimaisenan, Pirabasenan
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Regenerated cellulose fibre reinforced casein films: Effect of plasticizer and fibres on the film properties2014In: Macromolecular Research, ISSN 1598-5032, E-ISSN 2092-7673, Vol. 22, no 7, p. 701-709Article in journal (Refereed)
    Abstract [en]

    The idea of using man-made cellulosic fibres as reinforcement for casein films in this study was inspired by their well defined fibre diameter and availability in large quantity, eventually leading to a homogeneous high quality composite at low cost. The casein biofilms were fabricated by solution casting from an aqueous alkaline solution of the bovine milk protein casein in the presence of glycerol as a plasticizer, and the fibre-reinforced biocomposites were prepared by the addition of regenerated cellulose fibre to the casein casting solution with various amounts of glycerol. The effects of glycerol content and cellulose fibre reinforcements on the mechanical, thermal and physiological properties were characterized. The results showed that increasing glycerol content decreased the film strength, Young’s modulus and thermal stability with a gradual increase in the elongation. However, the tensile properties were noticeably improved when reinforced with cellulose fibre. The composite with 20 wt% glycerol and 20 wt% cellulose fibre showed the maximum tensile strength of 23.5 MPa and Young’s modulus of 1.5 GPa. The corresponding values for the composite with 30 wt% glycerol and the same fibre content were 15.1 MPa and 0.9 GPa, which were 2.3- and 3.2-fold higher compared to 30 wt% glycerol plasticized film. The thermal analysis revealed that the glass transition temperature and the thermal stability were decreased when the glycerol content was increased. Addition of cellulose fibres increased the glass transition temperature as well as the thermal stability. The gel electrophoresis (SDS-PAGE) analysis indicated that there was no significant decrease in the molecular weight of the casein protein during sample preparation. Scanning electron microscopy showed that the obtained composites with low glycerol content had adequate interfacial bonding, and Fourier transform IR spectroscopy confirmed the formation of molecular interactions between the cellulose fibres and the casein.

  • 88.
    Skrifvars, Mikael
    et al.
    University of Borås, School of Engineering.
    Baghaei, Behnaz
    University of Borås, School of Engineering.
    Kumar Ramamoorthy, Sunil
    University of Borås, School of Engineering.
    Rajan, Rathish
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Regenerated cellulose fibres for structural composites2014Conference paper (Other academic)
  • 89.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, School of Engineering.
    Persson, Anders
    University of Borås, Swedish School of Textiles.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Reusing Textile Waste As Reinforcements In Composites2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 17, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Polyester (PET) has wide applications in textile industries as textile fiber and its share continues to grow. Substantial quantities of cotton/polyester blend fabrics are disposed every year due to technical challenges, which pose a big environmental and waste-dumping problem. The aim of this study is to evaluate the potential of discarded cotton/PET fabrics as raw materials for composites. If their inherent reinforcement properties can be used in composites, an ecological footprint issue can be solved. In this study, we investigate three concepts for reuse of cotton/PET fabrics for composites: compression molding above the Tm of PETs, use of a matrix derived from renewable soybean oil, use of thermoplastic copolyester/polyester bi-component fibers as matrix. All three concepts have been explored to make them available for wider applications. The effects of processing parameters such as compression temperature, time and pressure are considered in all three cases. The third concept gives the most appealing properties, which combine good tensile properties with toughness; more than four times better tensile strength than the first concept; and 2.2 times better than the second concept.

  • 90.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Structural composites from cellulose reinforcements: material concepts and production strategies2014Conference paper (Refereed)
  • 91. Fatarella, Enrico
    et al.
    Mylläri, Ville
    Ruzzante, Marco
    Pogni, Rathish
    Baratto, Maria
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Syrjälä, Seppo
    Järvelä, Pentti
    Sulfonated polyetheretherketone/polypropylene polymer blends for the production of photoactive materials2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 8Article in journal (Refereed)
    Abstract [en]

    Sulfonated polyetheretherketone (SPEEK) was synthesized via a mono-substitution reaction of PEEK in concentrated sulphuric acid and was blended with polypropylene (PP) in 2–10%w/w concentration to be used for the production of photoactive thermoplastic products. SPEEK and SPEEK/PP blends were characterized using FTIR, DSC, TGA, NMR, rheology, SEM, and EPR. Under UV-Vis irradiation, stable benzophenone ketyl (BPK) radicals were generated by hydrogen extraction from PP. By increasing the amount of SPEEK in the polymer blend a linear increase in the BPK radicals was achieved according to the EPR data. DSC and TGA tests indicated weaknesses in the thermal stability of SPEEK but according to the rheological tests this should not have a major effect on processabililty. The optimal amount of SPEEK in the blend was obtained at 5%w/w. This concentration provided a good compromise between radical concentration, material processability, and cost

  • 92.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Wang, Yanfei
    Afshar, Shahrzad Javanshir
    Esmaeili, Nima
    Synthesis and Characterization of Bio-Based Thermosetting Resins from Lactic Acid and Glycerol2014In: Journal of Applied Polymer Science, E-ISSN 1097-4628, Vol. 131, no 12, p. 1-9Article in journal (Refereed)
    Abstract [en]

    A bio-based thermoset resin has been synthesized from glycerol reacted with lactic acid oligomers of three different chain lengths: n=3, 7 and 10. Lactic acid was first reacted with glycerol by direct condensation and the resulted branched molecule was then end-functionalized with methacrylic anhydride. The resins were characterized using FTIR, 13C-NMR spectroscopy to confirm the resins chemical structure and by DSC and DMTA to obtain the thermal properties. The resin flow viscosities were also measured using a Rheometer with different stress levels for each temperature used, as this is an important characteristic for resins which are intended to be used as a matrix in composite applications. The results showed that the resin with chain length n=3 have a better mechanical, thermal and rheological properties than resin with n=7 and 10. Also with its biobased content of 78% and glass transition temperature at 97°C makes it comparable with the commercial unsaturated polyester resins.

  • 93.
    Bakare, Fatimat
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Bashir, Tariq
    University of Borås, School of Engineering.
    Ingman, Petri
    Srivastava, Rajiv
    Synthesis and characterization of unsaturated lactic acid based thermoset bio-resins2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, p. 570-582Article in journal (Refereed)
    Abstract [en]

    Bio-based thermoset resins have been synthesized using lactic acid oligomers, which were functionalized with carbon–carbon double bonds, in order to allow their crosslinking by a free radical mechanism. Two different resin structures were synthesized. One resin was composed of an allyl alcohol terminated lactic acid oligomer, which was end-functionalized with methacrylic anhydride (MLA resin). The second resin was a mixture of the same allyl alcohol-lactic acid oligomer, and penthaerythritol. This mixture was end-functionalized with methacrylic anhydride, in order to get a methacrylate functionalized lactic acid oligomer, and methacrylate functionalized penthaerythritol (PMLA resin). The synthesized resins were characterized using FT-IR, 1H NMR and 13C NMR spectroscopy, differential scanning calorimetry as well as dynamic mechanical analysis to confirm the resin structure and reactivity. The flow viscosities were also measured in order to evaluate the suitability of the resins to be used as a matrix in composite applications. The results showed that the PMLA resin has better mechanical, thermal and rheological properties than the MLA resin, and both had properties which were comparable with a commercial unsaturated polyester resin. The high biobased content of 90% and the high glass transition temperature at 100 °C for the PMLA resin makes it an attractive candidate for composite applications where crude oil based unsaturated polyester resins are normally used.

  • 94.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Wang, Yanfei
    Afshar, Shahrzad Javanshir