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  • 101.
    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.

  • 102. Hooshmand, S.
    et al.
    Cho, S-W.
    University of Borås, School of Engineering.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Mathew, A.P.
    Oksdamn, K.
    Preparation of bio-nanocomposite fibers by melt spinning of cellulose acetate butyrate (CAB) and cellulose nanowhiskers (CNW)2012Conference paper (Other academic)
  • 103. 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.

  • 104. 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.

  • 105. Hooshmand, Saleh
    et al.
    Soroudi, Azadeh
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Electroconductive composite fibers by melt spinning of polypropylene/polyamide/carbon nanotubes2011In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 161, no 15-16, p. 1731-1737Article in journal (Refereed)
    Abstract [en]

    In this study, the blends of polypropylene/polyamide with carbon nanotubes (CNTs) have been prepared and melt spun to as-spun and drawn fibers. Thermal analysis showed that increasing the polyamide content, decreased the degree of crystallinity in the blends. Characterization of fibers showed that both conductivity and tensile strength have been improved by increasing the amount of polyamide in the blends as well as the melt blending temperature; furthermore, the morphology, electrical and mechanical properties of the blends were significantly influenced by adding 1 phr compatibilizer to the blend. The comparison between as-spun fibers and drawn fibers proved that although mechanical properties were improved after drawing, the electrical conductivity was decreased from the order of E−02 to E−06 (S/cm), due to applied draw-ratio of three.

  • 106. Hooshmand, Saleh
    et al.
    Soroudi, Azadeh
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Preparation of conductive composite fibers made from polypropylene, polyamide and multi-walled carbon nanotubes: electrical, mechanical and thermal characteristics2011Conference paper (Refereed)
  • 107.
    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.

  • 108.
    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.

  • 109.
    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.

  • 110. Jose, T
    et al.
    Joseph, A
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Thomas, S
    Joseph, K
    Thermal and crystallization behavior of cotton: Polypropylene commingled composite systems2010In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 31, no 8, p. 1487-1494Article in journal (Refereed)
    Abstract [en]

    Techniques like thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy were used to study the thermal and crystallization behavior of cotton-polypropylene (PP) commingled composite system. Thermal analysis was used to understand the structure-property relationship and also to quantify the amount of moisture and volatiles, which causes the deterioration of the composite performance. Thermal stability of the composite was found be intermediate between that of PP and cotton fibers. Presence of treated reinforcements had increased the crystallinity of PP. Also, fibers act as heterogeneous nucleants and favor the early crystallization of PP in the composites. The crystallization and onset crystallization temperature values were increased by the presence of cotton fibers. The theories of heterogeneous nucleation and crystal growth kinetics were used to explain the growth of transcrystalline layer (TCL) of PP on cotton fibers. The interfacial free energy difference for nucleation of PP on fiber was found to be smaller compared with that in the bulk PP. This favors the formation and growth of TCL. The thickness of TCL and radius of the spherulites increase with the increase in the crystallization temperature. Fiber surface roughness and thermal stresses facilitate the growth of transcrystallinity on cotton fiber.

  • 111.
    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.

  • 112.
    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)
  • 113.
    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

  • 114.
    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)
  • 115.
    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)
  • 116.
    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.

  • 117.
    Kalantar Mehrjerdi, Adib
    et al.
    University of Borås, School of Engineering.
    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.

  • 118.
    Kalantar Mehrjerdi, Adib
    et al.
    University of Borås, School of Engineering.
    Adl-Zarrabi, Bijan
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical and thermo-physical properties of high-density polyethylene modified with talc2013In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 129, no 4, p. 2128-2138Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to examine the physical, mechanical, and thermo-physical properties of high-density polyethylene (HDPE) modified with talc. Different weight fractions of talc (up to 35 wt %) were compounded with an HDPE matrix containing 2.5 wt % of carbon black (CB) in a twin-screw compounder. The composites were then processed by injection moulding to obtain specimens for testing. The results indicate that CB causes a significant decrease in the toughness, while talc not only enhances the thermal conductivity and thermo-physical properties of the composites but can also play a role in compensating for the negative effects of CB on impact resistance. The experimental data show that the presence of CB reduces the impact resistance of HDPE by up to 34%, while addition of up to 8 wt % talc can return this value to close to that of pure HDPE. No significant effect on the composite tensile yield and fracture strength was observed for either component at all concentrations. The thermal conductivity, thermal diffusivity, and specific density values of the composites increased almost linearly, but the increase in moisture absorption in the long term showed nonlinear behavior in the concentration range of the experiment.

  • 119.
    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.

  • 120.
    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.
    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.

  • 121.
    Kalantar Mehrjerdi, Adib
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical and morphological properties of talc filled high density polyethylene2013Conference paper (Other academic)
  • 122.
    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)
  • 123.
    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.

  • 124. Krishnaprasad, R
    et al.
    Veena, N.R.
    Maria, H.J.
    Rajan, R
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Joseph, K
    Mechanical and thermal properties of bamboo microfibril reinforced polyhydroxybutyrate biocomposites2009In: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 17, no 2, p. 109-114Article in journal (Refereed)
    Abstract [en]

    In the present investigation, microfibrils were extracted from raw bamboo and characterized using scanning electron microscope. Composites based on polyhydroxybutyrate (PHB) and bamboo microfibril were prepared with various microfibril loading. The mechanical and thermal properties of the resulting composites were measured. Tensile strength and impact strength of the composites were found to be increasing with increase in the loading of bamboo microfibrils, reached an optimum and thereafter decreased with further increase in microfibril loading. Percentage crystallinity was found to be increasing with increase in fibril loading. Thermal stability of the composite was higher than that of pure PHB. The composite could be developed further for various structural applications.

  • 125. Kumar, Hemanathan
    et al.
    Mahimaisenan, Pirabasenan
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Casein films and its composites with regenerated cellulose fibre for packaging applications2011Conference paper (Other academic)
    Abstract [en]

    A novel approach in the production of protein based films and composites were performed, using the bovine milk protein casein and regenerated cellulose fibres (lyocell). The films were prepared by first dissolving the casein protein in an aqueous alkaline solution in the presence of glycerol as a plasticizer. Further the composite films were prepared by the addition of fibres on aqueous alkaline solution with casein. The casein films and composites were thereafter prepared by casting the solution mixture on Teflon coated glass plate and drying for 48 hr. The effects of glycerol content and lyocell fibre reinforcements on the mechanical, thermal and physiological properties of the casein films were characterized. The results revealed that the increase in the addition of glycerol content decreases the tensile strength, young’s modulus, thermal stability of the film and increases the elongation percentage. Tensile property and thermal stability of the films was improved by the increase in the addition of the fibre content with a gradual decrease in the elongation percentage. The casein film made of 20% glycerol and 20% fibre content showed the maximum tensile strength of 23.5 MPa, E-modulus of 1.5 GPa and glass transition temperature (Tg) of 67.1±1.5 ºC. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that there was no significant change in the molecular weight of the protein during sample preparation. The inter molecular networks have taken place in the casein films and composites, when analyzed under Fourier Transform Infrared Spectroscopy (FTIR), and proper bonding between fibres and protein was observed by scanning electron microscope (SEM).

  • 126.
    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.

  • 127.
    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.

  • 128.
    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.

  • 129. 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)
  • 130. Lindström, Katarina
    et al.
    Ramamoorthy, Sunil Kumar
    University of Borås, School of Engineering.
    Persson, Anders
    University of Borås, Swedish School of Textiles.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Reuse of Waste Textiles For Composite Production2013Conference paper (Refereed)
    Abstract [en]

    Large amounts of cotton/PET textiles are wasted every year due to economically unfeasible separation of cotton and PET from waste textiles. These waste textiles were reused to form composites for technical applications and their properties were studied in this project. The waste textile, bed linen, used in this project comes from local hospital. The aim of this study is to produce composites from cotton/PET waste textiles and characterize by mechanical and thermal analysis. The effect of orientation of the fibers was studied and the processing parameters such as temperature, pressure and time of compression were optimized.

  • 131.
    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).
  • 132. Mahboubi Soufiani, Arman
    et al.
    Salehi, Massoud
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Persson, Maria
    Cho, Sung-Woo
    Thermomechanical properties of poly(lactic acid) films reinforced with hydroxyapatite and regenerated cellulose microfibers2014In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 131, no 20Article in journal (Refereed)
    Abstract [en]

    Novel composite films constituted of poly(lactic acid) (PLA), hydroxyapatite (HAp), and two types of regenerated cellulose fillers—particulate and fibrous type—were produced by melt extrusion in a twin-screw micro-compounder. The effect of the film composition on the tensile and dynamic mechanical behavior and the HAp dispersion in the PLA matrix were investigated thoroughly. Appearance of crazed regions and prevention of HAp aggregation in the PLA matrix were elucidated in the composites with up to 15 wt % particulate cellulose content, which was the main reason for only slight reduction in the tensile properties, and consequently trivial degradation of their pre-failure energy absorption as compared to neat PLA films. Superior dynamical energy storage capacities were obtained for the particulate cellulose modified composites, while their fibrous counterparts had not as good properties. Additionally, the anisotropic mechanical behavior obtained for the extruded composites should be favorable for use as biomaterials aimed at bone tissue engineering applications.

  • 133.
    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.

  • 134.
    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.

  • 135. Naseri, Atefeh
    et al.
    Naseri, Narges
    Airola, Karri
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Microscale Compounding of Polycaprolactone with Hydroxyapatite,β-Tricalcium Phosphate and Bioactive Glass for Biomedical Implant Applications2010Conference paper (Other academic)
  • 136. Persson, Maria
    et al.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Finnilä, Mikko A J
    Cho, Sung-Woo
    Tuukkanen, Juha
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Thermal and Mechanical Properties of PLA-HA Composite Fibres for Biomedical Applications2013Conference paper (Other academic)
  • 137. Persson, Maria
    et al.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Finnilä, Mikko
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Tuukkanen, Juha
    3D Woven Scaffolds of Melt-spun PLA Composite Fibres for Bone Regeneration2013Conference paper (Other academic)
    Abstract [en]

    Fibres are the basic units of textiles and are desirable as scaffold matrix material since they provide a large surface area to volume ratio. Using the textile technology, fibres can also be processed to form a variety of shapes and sizes, thus be used in different biological and medical applications. Poly(lactic acid) is a widely investigated material for use as scaffold matrix material and may be transformed into fibres either by melt spinning or solution spinning [1]. However, its lack of cell recognition signal has limited its use in tissue engineering applications [2]. Hydroxyapatite (HA) particles, which mimics the natural bone mineral has been proven to stimulate and promote cell attachment [3]. From that point of view, the aim of this study was to produce a PLA/HA composite fibres that could be used in a 3D woven scaffold for bone regeneration.

  • 138. Persson, Maria
    et al.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Tuukkanen, J
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Poly (Lactid Acid)/Hydroxipatite Composite Fibres for 3D Osteoconductive Woven Scaffolds2012Conference paper (Refereed)
    Abstract [en]

    This study presents a method to melt-spun biocompatible composite fibres from poly(lactic acid) (PLA) and nano-sized hydroxyapatite (HAp) particles. Different loading concentrations of HAp particles in the PLA fibres and solid-state draw-ratios (SSDR) were evaluated in order to study their influence on the mechanical, thermal and morphological properties. The results showed that the incorporation of the HAp particles was homogeneously distributed in the PLA fibres towards their surface and that the SSDR played an important role in order to improve the mechanical properties. The melt-spun PLA/HAp composite fibres, produced in this study, had also the potential to be processed into a fibrous scaffold, which was demonstrated by a 3D woven structure.

  • 139. Persson, Maria
    et al.
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    The effect of process variables on the properties of melt-spun poly(lactic acid) fibres for potential use as scaffold matrix materials2013In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 48, no 8, p. 3055-3066Article in journal (Refereed)
    Abstract [en]

    Biodegradable materials in the form of fibres and yarns have attracted increasing attention due to a large surface area and various geometric possibilities in three-dimensional polymeric scaffolds for tissue engineering applications. In this study, poly(lactic acid) fibres were produced by melt spinning and subsequent solid-state drawing in order to serve as matrix materials for fibre-based scaffold architectures. The processing of both monofilament and multifilament fibres as well as draw ratios and temperatures were investigated to analyze the effect of process variables on the properties. Two different polylactides with different molecular weight were studied and characterized in terms of their tensile and thermal properties and morphology. The relevance of fibre formation, solid-state drawing and drawing temperatures was clearly supported by the results, and it was shown that the physical properties, such as crystallinity, mechanical strength and ductility can be controlled largely by the drawing process. The obtained fibres demonstrated great potential to be further processed into biotextiles (woven, knitted, or nonwoven scaffolds) using the textile technologies.

  • 140.
    Persson, Maria
    et al.
    University of Borås, School of Engineering.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Woven Scaffolds of Melt-Spun Poly(lactic acid) Fibres for Bone Tissue Engineering2011Conference paper (Other academic)
  • 141. Persson, Maria
    et al.
    Lorite, Gabriela
    Cho, Sung-Woo
    Tuukkanen, Juha
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Melt Spinning of Poly(lactic acid) and Hydroxyapatite Composite Fibers: Influence of the Filler Content on the Fiber Properties2013In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, no 15, p. 6864-6872Article in journal (Refereed)
    Abstract [en]

    Composite fibers from poly(lactic acid) (PLA) and hydroxyapatite (HA) particles were prepared using melt spinning. Different loading concentrations of HA particles (i.e., 5, 10, 15, and 20 wt %) in the PLA fibers and solid-state draw ratios (SSDRs) were evaluated in order to investigate their influence on the fibers' morphology and thermal and mechanical properties. A scanning electron microscopy investigation indicated that the HA particles were homogeneously distributed in the PLA fibers. It was also revealed by atomic force microscopy and Fourier transform infrared spectroscopy that HA particles were located on the fiber surface, which is of importance for their intended application in biomedical textiles. Our results also suggest that the mechanical properties were independent of the loading concentration of the HA particles and that the SSDR played an important role in improving the mechanical properties of the composite fibers.

  • 142. Persson, Maria
    et al.
    Lorite, Gabriela
    Kokkonen, Hanna
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Tuukkanen, Juha
    Poly(lactic acid)/Hydroxyapatite Composite: a potential biomaterial for orthopedic applications2013Conference paper (Other academic)
  • 143. 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.

  • 144. Persson, Maria
    et al.
    Lorite, Gabriele
    Kokkonen, Hanna
    Cho, Sung-Woo
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Tuukkanen, Juha
    Initial cell attachment on hydroxyapatite/poly(lactic acid) composite films2013Conference paper (Other academic)
  • 145.
    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.

  • 146.
    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.

  • 147. Rahimiashtiyani, Samaneh
    et al.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Preparation and characterization of bio-nanocomposites from biobased thermoset resin, montmorillonite and natural fiber2011Conference paper (Other academic)
    Abstract [en]

    In this study bio-nanocomposites were manufactured, using a thermoset resin based on lactic acid and nanoclay (montmorillonite) as a matrix for flax fibers. The obtained composites were characterized by dynamic-mechanical thermal analysis (DMTA) and flexural testing. The aim of this study was to evaluate the mechanical properties of bio-nanocomposites without any surface treatment of the nanoclay and to use the resin/clay blend as a matrix for natural fiber composite. Results showed the nanoclay improved the mechanical properties.

  • 148. Rahimiashtiyani, Samaneh
    et al.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Preparation and characterization of bio-nanocomposites from biobased thermoset resin and montmorillonite2011Conference paper (Other academic)
    Abstract [en]

    Bio-nanocomposites are a new class of particle-based composites that have attracted much attention due to their environmental and economic advantages these years [1, 2]. In this study a biobased thermoset resin based on lactic acid was used and reinforced with montmorillonite (MMT). This resin consists of star-shaped oligomers of lactic acid, end-capped with methacrylate groups [3]. Thus, the resin can be cross-linked by a free radical polymerization. MMT consists of 1 nm thick aluminosilicate layers. Due to the high surface area, MMT has been evaluated as a reinforcement for several commercial polymers. While most commercial resins are non-polar, MMT is intrinsically polar. Therefore, MMT is usually surface treated in order to make it less polar. However, the resin used in this study is relatively polar and the purpose of this study was to evaluate if untreated MMT could be used to reinforce this resin. The curing was studied with isothermal differential scanning calorimetry (DSC) and the obtained composite were characterized by dynamic-mechanical thermal analysis (DMTA). Also transmission electronic spectroscopy (TEM) was used to characterize the structure. The result showed some improvements in mechanical properties. The DMTA results showed that the storage modulus and also loss modulus of the nanocomposite improved with respect to neat resin. Intercalated structures could be seen from the TEM micrographs.

  • 149. Rajan, KP
    et al.
    Veena, NR
    Maria, HJ
    Rajan, R
    Skrifvars, M
    University of Borås, School of Engineering.
    Joseph, K
    Extraction of bamboo microfibrils and development of biocomposites based on polyhydroxybutyrate and bamboo microfibrils2011In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 45, no 12, p. 1325-1329Article in journal (Refereed)
    Abstract [en]

    This investigation deals with the detailed procedure for the extraction of microfibrils from raw bamboo. The microfibrils obtained from raw bamboo were characterized using scanning electron microscope and the average diameter of the fibrils was found to be 10 mu m. These microfibrils were then incorporated into polyhydroxybutyrate (PHB) matrix using conventional plastic processing equipments. The impact strength values of the resulting composites indicate that there is an optimum loading of microfibrils in the PHB matrix, beyond which the effect of fibril loading is not significant.

  • 150. Rajan, R.
    et al.
    Sreekumar, P.A.
    Joseph, K.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Thermal and mechanical properties of chitosan reinforced polyhydroxybutyrate composites2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 124, no 4, p. 3357-3362Article in journal (Refereed)
    Abstract [en]

    The article reports the results of studies on the effect of chitosan (0, 5, 10, 20, 30, and 40 wt %) on thermal and mechanical properties of poly(hydroxybutyrate) composites. The addition of chitosan causes an increase in the glass transition temperature (Tg) while a decrease in the enthalpy of fusion (DHfus), crystallization (DHcry) and percentage of crystallinity as determined by differential scanning calorimeter (DSC). The thermogravimetric analysis reveals that high amount of chitosan decreases the thermal stability of the composites. The Young’s modulus of the composite increases and is high for the composite having 40 wt % of chitosan. Increase in the amount of chitosan decreases the elongation at break and impact strength of composites. Finally, the Young’s modulus of the composites has been compared with the theoretical predictions.

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