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  • 1.
    Akintunde, Moyinoluwa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Department of Microbiology, University of Ibadan, Ibadan, Nigeria.
    Adebayo-Tayo, B C
    Department of Microbiology, University of Ibadan, Ibadan, Nigeria.
    Ishola, M M
    Department of Energy and Environment, Göteborg Energi, Gothenburg, Sweden.
    Zamani, Akram
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bacterial Cellulose Production from agricultural Residues by two Komagataeibacter sp. Strains2022In: Bioengineered, ISSN 2165-5979, E-ISSN 2165-5987, Vol. 13, no 4, p. 10010-10025Article in journal (Refereed)
    Abstract [en]

    Agricultural residues are constantly increasing with increased farming processes, and improper disposal is detrimental to the environment. Majority of these waste residues are rich in lignocellulose, which makes them suitable substrate for bacterial fermentation in the production of valueadded products. In this study, bacterial cellulose (BC), a purer and better form of cellulose, was produced by two Komagataeibacter sp. isolated from rotten banana and kombucha drink using corncob (CC) and sugarcane bagasse (SCB) enzymatic hydrolyzate, under different fermentation conditions, that is, static, continuous, and intermittent agitation. The physicochemical and mechanical properties of the BC films were then investigated by Fourier Transformed Infrared Spectroscopy (FTIR), Thermogravimetry analysis, Field Emission Scanning Electron Microscopy (FESEM), and Dynamic mechanical analysis. Agitation gave a higher BC yield, with Komagataeibacter sp. CCUG73629 producing BC from CC with a dry weight of 1.6 g/L and 1.4 g/L under continuous and intermittent agitation, respectively, compared with that of 0.9 g/L in HS medium. While BC yield of dry weight up to 1.2 g/L was obtained from SCB by Komagataeibacter sp. CCUG73630 under continuous agitation compared to that of 0.3 g/L in HS medium. FTIR analysis showed BC bands associated with cellulose I, with high thermal stability. The FE-SEM analysis showed that BC fibers were highly ordered and densely packed. Although the BC produced by both strains showed similar physicochemical and morphological properties, the BC produced by the Komagataeibacter sp. CCUG73630 in CC under intermittent agitation had the best modulus of elasticity, 10.8 GPa and tensile strength, 70.9 MPa. [GRAPHICS]

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  • 2.
    Arya, Mina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Faculty of Textiles, Engineering and Business (Swedish Centre for Resource Recovery), University of Borås, 510 90 Borås, Sweden.
    Malmek, Else-Marie
    Juteborg AB, 426 79 Västra Frölunda, Sweden.
    Ecoist, Thomas Koch
    Ecoist AB, 262 72 Ängelholm, Sweden.
    Pettersson, Jocke
    RISE Research Institutes of Sweden, 431 53 Mölndal, Sweden.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business. Faculty of Textiles, Engineering and Business (Swedish Centre for Resource Recovery), University of Borås, 510 90 Borås, Sweden.
    Khalili, Pooria
    University of Borås, Faculty of Textiles, Engineering and Business. Faculty of Textiles, Engineering and Business (Swedish Centre for Resource Recovery), University of Borås, 510 90 Borås, Sweden.
    Enhancing Sustainability: Jute Fiber-Reinforced Bio-Based Sandwich Composites for Use in Battery Boxes2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 18, article id 3842Article in journal (Refereed)
    Abstract [en]

    The rising industrial demand for environmentally friendly and sustainable materials has shifted the attention from synthetic to natural fibers. Natural fibers provide advantages like affordability, lightweight nature, and renewability. Jute fibers’ substantial production potential and cost-efficiency have propelled current research in this field. In this study, the mechanical behavior (tensile, flexural, and interlaminar shear properties) of plasma-treated jute composite laminates and the flexural behavior of jute fabric-reinforced sandwich composites were investigated. Non-woven mat fiber (MFC), jute fiber (JFC), dried jute fiber (DJFC), and plasma-treated jute fiber (TJFC) composite laminates, as well as sandwich composites consisting of jute fabric bio-based unsaturated polyester (UPE) composite as facing material and polyethylene terephthalate (PET70 and PET100) and polyvinyl chloride (PVC) as core materials were fabricated to compare their functional properties. Plasma treatment of jute composite laminate had a positive effect on some of the mechanical properties, which led to an improvement in Young’s modulus (7.17 GPa) and tensile strength (53.61 MPa) of 14% and 8.5%, respectively, as well as, in flexural strength (93.71 MPa) and flexural modulus (5.20 GPa) of 24% and 35%, respectively, compared to those of JFC. In addition, the results demonstrated that the flexural properties of jute sandwich composites can be significantly enhanced by incorporating PET100 foams as core materials. 

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  • 3.
    Baghaei, Behnaz
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Johansson, Belinda
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business.
    All-Cellulose Composites Properties from Pre- and Post-Consumer Denim Wastes: Comparative Study2022In: Journal of Composites Science, E-ISSN 2504-477X, Vol. 6, no 5, article id 130Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    This study reports the recycling of discarded denim textiles by the production of all-cellulose composites (ACCs). Discarded denim fabrics were shredded into fibers and then made into nonwoven fabrics by carding and needle punching. The produced nonwoven fabrics were converted to ACCs by one-step and two-step methods using an ionic liquid (IL), 1-butyl-3-methyl imidazolium acetate ([BMIM][Ac]). In this study, the effect of different ACC manufacturing methods, denim fabrics with different contents (a 100% cotton denim (CO) and a blend material (cotton, poly-ester and elastane (BCO)) and reusing of IL as a recycled cellulose solvent on the mechanical pro-perties of the formed ACCs were investigated. The ACCs were characterized according to their tensile and impact properties, as well as their void content. Microscopic analysis was carried out to study the morphology of a cross-section of the formed composites. The choice of the one-step method with recycled IL, pure IL or with a blend material (BCO) had no influence on the tensile properties. Instead, the result showed that the two-step method, with and without DMSO, will influence the E-modulus but not the tensile strength. Regarding the impact properties of the samples, the only factor likely to influence the impact energy was the one-step method with CO and BCO.

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  • 4.
    Baghaei, Behnaz
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Högskolan i Borås.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    All-Cellulose Composites: A Review of RecentStudies on Structure, Properties and Applications2020In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, ISSN 1420-3049, Vol. 25, no 2Article in journal (Refereed)
    Abstract [en]

    Nowadays, there is greater demand for greener materials in societies due to environmental consciousness, depleting fossil fuels and growing ecological concerns. Within the foreseeable future, industries and suppliers will be required to be more aware of challenges faced due to the availability of resources and use more sustainable and renewable raw materials. In this context, cellulose can be expected to become a vital resource for materials owing to its abundance, versatility as a biopolymer, several different forms and potential applications. Thus, all-cellulose composites (ACCs) have gained significant research interest in recent years. ACC is a class of biocomposites in which the matrix is a dissolved and regenerated cellulose, while the reinforcement is undissolved or partly dissolved cellulose. This review paper is intended to provide a brief outline of works that cover recent progress in the manufacturing and processing techniques for ACCs, various cellulose sources, solvents and antisolvents, as well as their properties.

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  • 5.
    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.

  • 6.
    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.

  • 7.
    Bátori, Veronika
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Zamani, Akram
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pectin-based Composites2017In: Handbook of Composites from Renewable Materials: Biodegradable Materials, John Wiley & Sons, 2017, p. 487-518Chapter in book (Other academic)
    Abstract [en]

    One third of the cell wall of vascular plants is composed of pectin, which serves as the cementing material for the cellulosic network, behaving as a stabilized gel. Industrially, pectin is produced from juice and sugar production waste. Different sources and extraction conditions result in diversity in characteristics and applications of pectin. Most commonly, pectin is used in the food industry as a gelling and thickening agent and it is favored in the pharmaceutical industry as a carrier for colon-specific drugs. Pectin has good potential to be utilized as a matrix in production of environmentally friendly film packaging as well as biocomposite materials. Pectin is sensitive to chemical reactions and promotes the homogeneous immobilization of cells, genes, and proteins. However, due to limited mechanical properties pectin is not used for structural applications but instead rather for composites in which its biodegradable properties can be utilized. Pectin is often reinforced with hydroxyapatite and biphasic calcium phosphate for bone regeneration and tissue engineering applications. It can also be used as a biosorbent for copper removal from aqueous solutions. Active packaging of nanohybrids composed of pectin and halloysite nanotubes that are loaded with rosemary essential oil is another application of pectin-based composites.

  • 8.
    Cong, X.
    et al.
    Faculty of Science and Engineering, University of Nottingham Ningbo China, Ningbo 315100, China.
    Khalili, Pooria
    University of Borås, Faculty of Textiles, Engineering and Business.
    Zhu, C.
    Faculty of Science and Engineering, University of Nottingham Ningbo China, Ningbo 315100, China.
    Li, S.
    Faculty of Science and Engineering, University of Nottingham Ningbo China, Ningbo 315100, China.
    Li, J.
    National Engineering Technology Research Centre of Flame Retardant Material, School of Materials, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China.
    Rudd, C.
    James Cook University, Singapore 387380, Singapore.
    Liu, X.
    Faculty of Science and Engineering, University of Nottingham Ningbo China, Ningbo 315100, China.
    Investigation of fire protection performance and mechanical properties of thin-ply bio-epoxy composites2021In: Polymers, E-ISSN 2073-4360, Vol. 13, no 5, p. 1-13, article id 731Article in journal (Refereed)
    Abstract [en]

    Hybrid composites composed of bio-based thin-ply carbon fibre prepreg and flame-retardant mats (E20MI) have been produced to investigate the effects of laminate design on their fire protection performance and mechanical properties. These flame-retardant mats rely primarily on expandable graphite, mineral wool and glass fibre to generate a thermal barrier that releases incom-bustible gasses and protects the underlying material. A flame retardant (FR) mat is incorporated into the carbon fibre bio-based polymeric laminate and the relationship between the fire protection properties and mechanical properties is investigated. Hybrid composite laminates containing FR mats either at the exterior surfaces or embedded 2-plies deep have been tested by the limited oxygen index (LOI), vertical burning test and cone calorimetry. The addition of the surface or embedded E20MI flame retardant mats resulted in an improvement from a base line of 33.1% to 47.5% and 45.8%, respectively. All laminates passed the vertical burning test standard of FAR 25.853. Cone calorimeter data revealed an increase in the time to ignition (TTI) for the hybrid composites containing the FR mat, while the peak of heat release rate (PHRR) and total heat release (TTR) were greatly reduced. Furthermore, the maximum average rate of heat emission (MARHE) values indicated that both composites with flame retardant mats had achieved the requirements of EN 45545-2. However, the tensile strengths of laminates with surface or embedded flame-retardant mats were reduced from 1215.94 MPa to 885.92 MPa and 975.48 MPa, respectively. Similarly, the bending strength was reduced from 836.41 MPa to 767.03 MPa and 811.36 MPa, respectively. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

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  • 9.
    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.

  • 10.
    Fulmali, Abhinav Omprakash
    et al.
    FRP Composites Laboratory, Metallurgical and Materials Engineering Department National Institute of Technology Rourkela India.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Prusty, Rajesh Kumar
    FRP Composites Laboratory, Metallurgical and Materials Engineering Department National Institute of Technology Rourkela India;Center for Nanomaterials National Institute of Technology Rourkela India.
    Water diffusion kinetics study at different hydrothermal bath temperatures and subsequent durability studies of CNT embedded fibrous polymeric composites: Roles of CNT content, functionalization and in‐situ testing temperature2023In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 140, no 11Article in journal (Refereed)
    Abstract [en]

    Although structural polymers like epoxy are extensively used in marine applications over metallic structures, environmental water tends to ingress into this polymer which may affect its long-term durability. The extent of degradation caused by the absorbed water on polymeric composite's mechanical properties depends on the water diffusion mechanism, environmental temperature and subsequent reversible and irreversible chemical restructuring of the polymer. In this study, hydrothermal conditioning behavior of glass fiber reinforced epoxy (GE) composites with varying (0.1, 0.3, and 0.5) wt.% of pristine and functionalized carbon nanotubes (CNTs and FCNTs) was studied at 15°C (Low-Temperature Hydrothermal Conditioning (LTHC)) and 50°C (Elevated-Temperature Hydrothermal Conditioning (ETHC)) water baths. The changes in chemical bonding characteristics and glass transition temperature of GE composite due to above mentioned factors have been studied by Fourier transformed infrared spectroscopy and differential scanning calorimetry. The gravimetric analysis was employed to monitor the water uptake kinetics of the composites and flexural strength of conditioned composites after 50 days of conditioning and saturation was study to understand the effect of water sorption. Experimental results revealed that, FCNTs greatly hinders the water absorption through the interfaces at LTHC, as the equilibrium water content of 0.1FCNT-GE composite was ~9.5% and ~3.0% and Diffusion coefficient was ~60.0% and ~15.5% lower than the GE and 0.1CNT-GE composites, respectively at LTHC. At LTHC, the water saturated 0.1FCNT-GE composites exhibited superior flexural strength than GE and 0.1CNT-GE composites. At ETHC, generation of hygroscopic stresses and unfavorable stresses at the weak CNT/polymer interface adversely affected the 0.1CNT-GE composites water resistance compared to 0.1FCNT-GE composites with stronger FCNT/polymer interface. The extent of recovery in the flexural strength was evaluated by complete desorption of water-saturated specimens. Finally, a fractography study was conducted to understand the variation in the well-being of the glass fiber/polymer and nanotube/polymer interface due to mentioned varying factors.

  • 11.
    Gaurangkumar Mistry, Snehaben
    University of Borås, Faculty of Textiles, Engineering and Business.
    Development Of Bio-Based Thermosetting Resins2021Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Thermoset polymers are widely used polymers in the world, but Increase in global plastic pollution and lack of fossil fuel stimulates intense research towards environmentally sustainable materials. Bio-based unsaturated polyesters (UPs) would be an excellent solution to replace oil-based synthetic polyesters. Most of the unsaturated polyesters have been synthesised by ring opening polymerisation (ROP) of cyclic esters or lactides. 

    In this study, different resins were developed using different initiators such as isosorbide (IS),1,4 butanediol (BD), and cis-2 butene 1,4 diol (C2BD) with monomers like lactide (L) and alpha angelica lactone (AAL) through the ring opening polymerisation process. The produced resins were further characterised by using Fourier Transform Infrared Spectroscopy (FTIR),Nuclear Magnetic Resonance (NMR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimeter (DSC), and Dynamic Mechanical Analysis (DMA). 

    Synthesis of resin with lactone monomer was not successful while with lactide monomer it was successful. IS-based resin showed better thermal properties compared to other obtained resins. Tg value of IS containing resin was 63°C, thermal stability up to 235°C and Storage modulus about 3841 MPa. These values are comparable with other bio-based resins produced using the same monomer. 

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    DEVELOPMENT OF BIO-BASED THERMOSETTING RESINS
  • 12.
    Johansson, Matilda
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dhakal, H. N.
    Advanced Polymers and Composites (APC) Research Group, School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, Hampshire PO1 3DJ, UK.
    Effect of lignin acetylation on the mechanical properties of lignin-poly-lactic acid biocomposites for advanced applications2023In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 202, article id 117049Article in journal (Refereed)
    Abstract [en]

    Bioplastics that possess characteristics like durability and low cost are desired for versatile applications in industries such as automotive manufacturing, marine transport manufacturing, aerospace applications, and the building industry. The automotive industry is an example of an industry that is now shifting towards a more focused approach addressing the issue concerning sustainability and the development of sustainable material. To achieve a lightweight and sustainable construction, one of the methods used by the automotive original equipment manufacturers is by substituting conventional fossil-based, non-renewable composites, and metallic materials with a bio-based alternative. One of the drawbacks with biobased polymers can be the poor interfacial adhesion, leading to poor mechanical properties when compares to conventional material. The aim of this research is to investigate if a low-cost by-product could be used as a component in a composite matrix material in the automotive industry to reduce the final weight and increase the non-petrochemical material usage of composite material without compromising the thermal and mechanicals properties demanded. In this research, lignin was chemically altered by esterification the functional groups to increase the compatibility with polylactic acid. The esterification was performed with the use of acetic acid anhydride and pyridine. To evaluate and determine the esterification, Fourier transform Infrared Spectroscopy was used. By blending the modified lignin with polylactic acid the intention was to improve the thermomechanical properties and the interfacial linkage between the components. The effects of lignin acetylation on the tensile properties, impact strength, and thermal stability and moisture repellence behaviour were investigated. According to the experimental results the modification of lignin, increased the impact strength for all the blends containing acetylated lignin compares to pristine lignin. The largest increase observed was for blends containing 20 wt% acetylated lignin and polylactic acid, which resulted in a 74% improvement compared with the blend composed of pristine lignin and polylactic acid. Similarly, the thermal stability was improved significantly with acetylation of the lignin. Moreover, the moisture repellence behaviour was also increased. The reason for the improved properties can be explained by the better interfacial compatibility between lignin and polylactic acid matrix. An increased thermal stability and a moisture repellent behaviour of the blends containing chemically modified lignin could be observed when compared with neat polylactic acid which makes the acetylation treatment of lignin a possible approach for the future of biocomposite production. 

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  • 13.
    Khalili, Pooria
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kádár, R.
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Blinzler, B.
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg.
    Impregnation behaviour of regenerated cellulose fabric Elium® composite: Experiment, simulation and analytical solution2021In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 10, p. 66-73Article in journal (Refereed)
    Abstract [en]

    Filling time and volume fill prediction of long and complex parts produced using the method of resin infusion is of prominent importance. Fibre volume fraction, reinforcement type and composite laminate thickness significantly affect the manufacturing behaviour. It is crucial to have an estimate of fabrication parameters such as filling time. The PAM-RTM (resin transfer moulding) commercial software package makes it possible to characterize the production parameters in connection with lab scale experiments. In this work, simulation tools demonstrate an accurate prediction of the resin infusion process of pulp-based fabrics and characterization of the dynamic phenomena are verified using the analytical solution for a simple part. The accurate prediction for fabrication of pulp-based fabric Elium® composite demonstrated here can be beneficial for scaling up the composite part size and production speed. The filling time was accurately predicted until 270 s for the volume fill of 10-100% using the software tool and analytical solution. This proves the rayon fabric processing capabilities as a reinforcement for industry related projects and opens for the possibility of infusion process optimization.

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  • 14.
    Khalili, Pooria
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dhakal, Hom Nath
    Advanced Polymers and Composites (APC), School of Mechanical Design and Engineering, University of Portsmouth, Portsmouth, PO1 3DJ, United Kingdom.
    Jiang, Chulin
    Advanced Polymers and Composites (APC), School of Mechanical Design and Engineering, University of Portsmouth, Portsmouth, PO1 3DJ, United Kingdom.
    Regenerated cellulose fabric reinforced bio-based polypropylene sandwich composites: fabrication, mechanical performance and analytical modelling2023In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 22, p. 3423-3435Article in journal (Refereed)
    Abstract [en]

    Sandwich composites were fabricated successfully with the balsa wood as core material and regenerated cellulose fabric bio-based polypropylene (PP) composite skins. The regenerated cellulose fabric PP composites were produced using two different methods: the conventional stacking lay-up and directly using PP pellets. Sandwich composites were made using the hot press equipment with the customized mold. The sandwich composite system and bio-composite laminate were designed to achieve very close weight to compare the key mechanical properties that each design can bear. It was evidenced from the experimental results that 416% increase in the bending load bearing property of the part can be obtained when sandwich structure was used. These experimental results were in close agreement with one of the analytical modelling utilised. The drop weight impact test results demonstrated that the sandwich specimen is capable of withstanding more than 6 kN load and absorbing the impact energy of 28.37 J.

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  • 15.
    Khalili, Pooria
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Erturk, Semih Ertürk
    Department of Industrial and Materials Science, Chalmers University of Technology, 412 96 Gothenburg, Sweden.
    Fabrication: Mechanical Testing and Structural Simulation of Regenerated Cellulose Fabric Elium(R) Thermoplastic Composite System2021In: Polymers, E-ISSN 2073-4360, Vol. 13, no 17Article in journal (Refereed)
    Abstract [en]

    Regenerated cellulose fibres are an important part of the forest industry, and they can be used in the form of fabrics as reinforcement materials. Similar to the natural fibres (NFs), such as flax, hemp and jute, that are widely used in the automotive industry, these fibres possess good potential to be used for semi-structural applications. In this work, the mechanical properties of regenerated cellulose fabric-reinforced poly methyl methacrylate (PMMA) (Elium(R)) composite were investigated and compared with those of its natural fibre composite counterparts. The developed composite demonstrated higher tensile strength and ductility, as well as comparable flexural properties with those of NF-reinforced epoxy and Elium(R) composite systems, whereas the Young's modulus was lower. The glass transition temperature demonstrated a value competitive (107.7 degrees C) with that of other NF composites. Then, the behavior of the bio-composite under bending and loading was simulated, and a materials model was used to simulate the behavior of a car door panel in a flexural scenario. Modelling can contribute to predicting the structural behavior of the bio-based thermoplastic composite for secondary applications, which is the aim of this work. Finite element simulations were performed to assess the deflection and force transfer mechanism for the car door interior.

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  • 16.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kuzhanthaivelu, Gauthaman
    Bohlén, Martin
    Research Institutes of Sweden.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Waste Management Option for Bioplastics Alongside Conventional Plastics2019In: IRC 2019 International Research Conference Proceedings, 2019Conference paper (Refereed)
    Abstract [en]

    Bioplastics can be defined as polymers derived partly or completely from biomass. Bioplastics can be biodegradable such as polylactic acid (PLA) and polyhydroxyalkonoates (PHA); or non-biodegradable (biobased polyethylene (bio-PE), polypropylene (bio-PP), polyethylene terephthalate (bio-PET)). The usage of such bioplastics is expected to increase in the future due to new found interest in sustainable materials. At the same time, these plastics become a new type of waste in the recycling stream. Most countries do not have separate bioplastics collection for it to be recycled or composted. After a brief introduction of bioplastics such as PLA in UK, these plastics are once again replaced by conventional plastics by many establishments due to lack of commercial composting. Recycling companies fear the contamination of conventional plastic in the recycling stream and they said they would have to invest in expensive new equipment to separate bioplastics and recycle it separately. Bioplastics are seen as a threat to the recycling industry as bioplastics may degrade during the mechanical recycling process and the properties of the recycled plastics are seriously impacted. This project studies what happens when bioplastics contaminate conventional plastics.

    Three commonly used conventional plastics were selected for this study: polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET). In order to simulate contamination, two biopolymers, either polyhydroxyalkanoate (PHA) or thermoplastic starch (TPS) were blended with the conventional polymers. The amount of bioplastics in conventional plastics was either 1% or 5%. The blended plastics were processed again to see the effect of degradation. Mechanical, thermal and morphological properties of these plastics were characterized.

     

    The results from contamination showed that the tensile strength and the modulus of PE was almost unaffected whereas the elongation is clearly reduced indicating the increase in brittleness of the plastic. Generally, it can be said that PP is slightly more sensitive to the contamination than PE. This can be explained by the fact that the melting point of PP is higher than for PE and as a consequence, the biopolymer will degrade more quickly. However, the reduction of the tensile properties for PP is relatively modest. It is also important to notice that when plastics are recovered, there will always be a contamination that will reduce the material properties. The reduction of the tensile properties is not necessary larger than if a non-biodegradable polymer would have contaminated PE or PP. The Charpy impact strength is generally a more sensitive test method towards contamination. Again, PE is relatively unaffected by the contamination but for PP there is a relatively large reduction of the impact properties already at 1% contamination.

    PET is polyester and it is by its very nature more sensitive to degradation than PE and PP. PET also have a much higher melting point than PE and PP and as a consequence the biopolymer will quickly degrade at the processing temperature of PET. As for the tensile strength, PET can tolerate 1% contamination without any reduction of the tensile strength. However, when the impact strength is examined, it is clear that already at 1% contamination, there is a strong reduction of the properties. It can also be seen that presence of TPS is more detrimental to PET than PHA is. This can be explained by the fact that TPS contain reactive hydroxyl groups that can react with the ester bond of PET. This will in other words lead to degradation of PET.

    The thermal properties show the change in the crystallinity. As a general conclusion, it can be said that the plastics become less crystalline when contaminated. The blends were also characterized by SEM. Biphasic morphology can be seen as the two polymers are not truly blendable which also contributes to reduced mechanical properties. Recycling of the contaminated polymer shows an increase in crystallinity. This means that when the polymers are processed, polymer degradation occur causing the polymer chains to gradually become shorter which will enhance the crystallization process.

    The study shows that PE is relatively robust againt contamination, while polypropylene (PP) is somewhat more sensitive and polyethylene terephthalate (PET) can be quite sensitive towards contamination.

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  • 17.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Prusty, Rajesh Kumar
    Center for Nanomaterials, National Institute of Technology, Rourkela, India.
    Fulmali, Abhinav Omprakash
    FRP Composites Laboratory, Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, India.
    Functionalization of Carbon Nanotube2021In: Handbook of Carbon Nanotubes / [ed] Jiji Abraham, Sabu Thomas, Nandakumar Kalarikkal, Springer, 2021Chapter in book (Refereed)
    Abstract [en]

    One-dimensional carbon nanotubes (CNTs) have outstanding mechanical properties, making them a good candidate for reinforcement application in polymer and fiber-reinforced polymer composites. Superior properties of the CNTs are exploited regularly by reinforcing these nanotubes in a polymer matrix. However, strong Van der Waals interaction energy of tube-tube contact, high electrostatic interaction between the tubes, small tube size, and large surface area of the tubes render CNT dispersion a problematic task. Therefore, to improve its dispersion and alignment in the composite, researchers have developed innovative techniques to strengthen the properties of the composite. For achieving optimum and reproducible mechanical properties in a composite, fine dispersion of CNTs, their alignment, and strong interfacial adhesion with polymer is a demand to be guaranteed. In this chapter, the principles and techniques for uniform dispersion and alignment of CNTs in the polymer and fiber-reinforced polymer composite are discussed.

  • 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.
    Malm, Veronica
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Seoane, Fernando
    University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fused deposition modelling – Towards 3D printed electrodes on fabric for surface electromyography (sEMG)2018Conference paper (Other academic)
    Abstract [en]

    Surface electromyography (sEMG) monitoring has promising applications within the field of human robot communication where wearable electrodes are used as the interface. This research investigates the production of flexible 3D printed electrodes using electrically conductive filaments, of thermoplastic polyurethane containing carbon black, and polyester fabric as substrate. Dry 3D printed electrodes of varying thickness, due to increased number of layers, were compared to conventional electrolytic gel electrodes. Initial tests show that the volume resistivity of 3D printed electrodes increased with increased number of layers. This because, with increased number of layers the diffusion between layers deteriorates and hinders conductive particle connections. Additional heat-treatments using hot press plates to improve diffusion between layers were promising as volume resistivity decreased with 200 % for all samples. As a first step to evaluate the 3D printed electrodes, skin-electrode impedance measurements were performed, and compared with measurements of conventional electrodes. Results showed that resistance and reactance versus frequency curves had similar trending slopes, decreasing with increasing frequency. However, this corresponded only between the thinnest (200 μm) 3D-printed dry electrode having a volume resistivity of 6.2 Ω cm and the conventional gel electrode. Future studies regarding the influence of platform and extruder temperature are planned for, focusing on improved diffusion between layers and increased conduction for proper electron transfer. 

  • 20.
    Movaffaghi, Hamid
    et al.
    Department of Resource Recovery and Building Technology, Faculty of Textiles, Engineering and Business, University of Borås, Borås, Sweden;Department of Construction Engineering and Lighting Science, Jönköping University, Jönköping, Sweden.
    Pyykkö, Johan
    University of Borås, Faculty of Textiles, Engineering and Business. Department of Resource Recovery and Building Technology, Faculty of Textiles, Engineering and Business, University of Borås, Borås, Sweden;Division of Applied Mechanics, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Vibration performance of timber-concrete composite floor section –verification and validation of analytical and numerical results based on experimental data2022In: Civil engineering and environmental systems (Print), ISSN 1028-6608, E-ISSN 1029-0249, p. 1-20Article in journal (Refereed)
    Abstract [en]

    Vibration performance of a one-way simply supported timber-concrete composite (TCC) floor section has been studied using analytical as well as numerical methods. Focal points have been verification and validation of results from analytical and numerical calculations of vibration response based on experimental data. For the analytical calculations, floor bending stiffness and vibrational response are determined from methods proposed in the current and revised versions of Eurocode 5. The numerical calculations based on the finite element (FE) method are done using 3D solid elements with orthotropic material parameters. When comparing the results of the FE analysis, better agreement with the experimental data is reached for the fundamental frequency when 3D solid elements are used rather than 3D beam elements. Furthermore, better agreement with the experimental data is reached for RMS acceleration by FE analysis rather than the method based on Eurocode 5. For detailed analysis, the authors suggest performing dynamic FE analysis and calculating vibration response from the TCC floor’s modal responses as eigenmodes and natural eigenfrequencies below 40 Hz. For future studies, it is recommended that the verification of vibration response may be accomplished by applying standard EN 16929.

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  • 21.
    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.

  • 22.
    Noè, C.
    et al.
    Department of Applied Science and Technology, Politecnico di Torino.
    Hakkarainen, M.
    Department of Fibre and Polymer Technology, KTH Royal Institute of Technology.
    Malburet, S.
    Specific Polymers.
    Graillot, A.
    Specific Polymers.
    Adekunle, Kayode
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sangermano, M.
    Department of Applied Science and Technology, Politecnico di Torino.
    Frontal-Photopolymerization of Fully Biobased Epoxy Composites2022In: Macromolecular materials and engineering, ISSN 1438-7492, E-ISSN 1439-2054Article in journal (Refereed)
    Abstract [en]

    The radical-induced cationic frontal photopolymerization (RICFP) of fully biobased epoxy composites is successfully demonstrated. This curing strategy considerably reduces the curing time and improves the efficiency of the composite fabrication. Two different natural fiber fabrics made of cellulose and flax fibers are embedded in two epoxy matrices, one derived from vanillin (diglycidylether of vanillyl alcohol-DGEVA) and the other from petroleum (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate-CE). After RICFP the composites are characterized by means of dynamic mechanical thermal analysis and tensile tests. The mechanical properties improved with increasing fiber content, confirming a strong adhesion between the matrix and the reinforcing fiber fabrics, which is further evidenced by scanning electron microscopy analyses of the fracture surfaces. Furthermore, these fully bio-based composites possess comparable or even higher mechanical strength compared with the corresponding epoxy composites fabricated with conventional CE resin. A promising facile route to high-performing natural fiber-biobased epoxy resin composites is presented. © 2022 Wiley-VCH GmbH

  • 23.
    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.

  • 24.
    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, 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.

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  • 25.
    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.

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  • 26.
    Saleem, Anjum
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Medina, Luisa
    Department of Applied Logistics and Polymer Sciences, University of Applied Sciences Kaiserslautern, 67659 Kaiserslautern, Germany.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Improvement of performance profile of acrylic based polyester bio-composites by bast/basalt fibers hybridization for automotive applications2021In: Journal of Composites Science, ISSN 2504-477X, Vol. 5, no 4, article id 100Article in journal (Refereed)
    Abstract [en]

    New technologies in the automotive industry require lightweight, environment-friendly, and mechanically strong materials. Bast fibers such as kenaf, flax, and hemp reinforced polymers are frequently used composites in semi-structural applications in industry. However, the low mechanical properties of bast fibers limit the applications of these composites in structural applications. The work presented here aims to enhance the mechanical property profile of bast fiber reinforced acrylic-based polyester resin composites by hybridization with basalt fibers. The hybridization was studied in three resin forms, solution, dispersion, and a mixture of solution and dispersion resin forms. The composites were prepared by established processing methods such as carding, resin impregnation, and compression molding. The composites were characterized for their mechanical (tensile, flexural, and Charpy impact strength), thermal, and morphological properties. The mechanical performance of hybrid bast/basalt fiber composites was significantly improved compared to their respective bast fiber composites. For hybrid composites, the specific flexural modulus and strength were on an average about 21 and 19% higher, specific tensile modulus and strength about 31 and 16% higher, respectively, and the specific impact energy was 13% higher than bast fiber reinforced composites. The statistical significance of the results was analyzed using one-way analysis of variance. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

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  • 27.
    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.

  • 28.
    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)
  • 29.
    Syrén, Felicia
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Peterson, Joel
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Effects of Microwave Treatment in Immersed Conditions on the Mechanical Properties of Jute Yarn2021In: Fibers, E-ISSN 2079-6439, Vol. 9, no 7Article in journal (Other academic)
    Abstract [en]

    The versatile bast fiber jute has environmental benefits compared to glass fibers. However, for jute to be used in a composite, the fiber properties need to be altered. This study aims to improve the mechanical properties of jute yarn to make it more suitable for technical applications as a composite. To alter its mechanical properties, jute yarn was immersed in water during microwave treatment. The time and power of the microwave settings differed between runs. Two states of the yarn were tested: fastened and un-fastened. Tensile testing was used at the yarn and fiber level, followed by Fourier-transform infrared spectroscopy (FTIR) and microscopy. The treatment result demonstrated the ability to increase the elongation of the jute yarn by 70%. The tenacity was also increased by 34% in the fastened state and 20% in the un-fastened state. FTIR showed that no change in the molecular structure occurred. The treatments resulted in a change of yarn thickness depending on the state of the yarn. The results indicate that microwave treatment can be used to make jute more suitable for technical applications depending on the microwave treatment parameters.

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  • 30.
    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.

  • 31.
    Uusi-Tarkka, Eija-Katriina
    et al.
    University of Eastern Finland, Finland.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Haapala, Antti
    University of Eastern Finland, Finland.
    Fabricating sustainable all-cellulose composites2021In: Applied Sciences, E-ISSN 2076-3417, Vol. 11, no 21, article id 10069Article in journal (Refereed)
    Abstract [en]

    Climate change, waste disposal challenges, and emissions generated by the manufacture of non-renewable materials are driving forces behind the production of more sustainable composite materials. All-cellulose composites (ACCs) originate from renewable biomass, such as trees and other plants, and are considered fully biodegradable. Dissolving cellulose is a common part of manufacturing ACCs, and currently there is a lot of research focused on effective, but also more environmentally friendly cellulose solvents. There are several beneficial properties of ACC materials that make them competitive: light weight, recyclability, low toxicity, good optical, mechanical, and gas barrier properties, and abundance of renewable plant-based raw material. The most prominent ACC applications are currently found in the food packing, medical, technical and vehicle industries. All-cellulose nanocomposites (ACNCs) expand the current research field and can offer a variety of more specific and functional applications. This review provides an overview of the manufacture of sustainable ACCs from lignocellulose, purified cellulose, and cellulosic textiles. There is an introduction of the cellulose dissolution practices of creating ACCs that are currently researched, the structure of cellulose during complete or partial dissolution is discussed, and a brief overview of factors which influence composite properties is presented. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

  • 32.
    Uusi-Tarkka, Eija-Katriina
    et al.
    School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, FI-80101 Joensuu, Finland.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery, Faculty of Textiles, Engineering and Business, University of Borås, SE-50190 Borås, Sweden.
    Khalili, Pooria
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery, Faculty of Textiles, Engineering and Business, University of Borås, SE-50190 Borås, Sweden.
    Heräjärvi, Henrik
    Natural Resources Institute Finland, FI-80100 Joensuu, Finland.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business. Department of Textile Technology, Faculty of Textiles, Engineering and Business, University of Borås, SE-50190 Borås, Sweden.
    Haapala, Antti
    School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, FI-80101 Joensuu, Finland;FSCN Research Centre, Mid Sweden University, SE-85170 Sundsvall, Sweden.
    Mechanical and Thermal Properties of Wood-Fiber-Based All-Cellulose Composites and Cellulose-Polypropylene Biocomposites2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 3, article id 475Article in journal (Refereed)
    Abstract [en]

    This article explores wood-fiber-based fabrics containing Lyocell yarn in the warp and Spinnova–Lyocell (60%/40%) yarn in the weft, which are used to form unidirectional all-cellulose composites (ACC) through partial dilution in a NaOH–urea solution. The aim is to investigate the role of the yarn orientation in composites, which was conducted by measuring the tensile properties in both the 0° and 90° directions. As a reference, thermoplastic biocomposites were prepared from the same fabrics, with biobased polypropylene (PP) as the matrix. We also compared the mechanical and thermal properties of the ACC and PP biocomposites. The following experiments were carried out: tensile test, TGA, DSC, DMA, water absorption test and SEM. The study found no significant difference in tensile strength regarding the Spinnova–Lyocell orientation between ACC and PP biocomposites, while the composite tensile strength was clearly higher in the warp (Lyocell) direction for both composite variants. Elongation at break doubled in ACC in the Lyocell direction compared with the other samples. Thermal analysis showed that mass reduction started at a lower temperature for ACC, but the thermal stability was higher compared with the PP biocomposites. Maximum thermal degradation temperature was measured as being 352 °C for ACC and 466 °C for neat PP, and the PP biocomposites had two peaks in the same temperature range (340–474 °C) as ACC and neat PP combined. ACCs absorbed 93% of their own dry weight in water in just one hour, whereas the PP biocomposites BC2 and BC4 absorbed only 10% and 6%, respectively. The study highlights the different properties of ACC and PP reference biocomposites that could lead to further development and research of commercial applications for ACC.

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  • 33.
    Xu, Yunsheng
    et al.
    Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44, Stockholm, Sweden.
    Adekunle, Kayode
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hakkarainen, Minna
    Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44, Stockholm, Sweden.
    Methacrylated lignosulfonate as compatibilizer for flax fiber reinforced biocomposites with soybean-derived polyester matrix2020In: Composites Communications, ISSN 2452-2139Article in journal (Refereed)
    Abstract [en]

    The poor adhesion between natural fibers and polymer matrix restricts the mechanical performance of natural fiber reinforced composites. Here, lignosulfonate was methacrylated and evaluated as a potential compatibilizer for flax fiber reinforced soybean-derived polyester thermosets. Significant improvement in both tensile and flexural properties of the fiber composites were achieved when the flax fiber mat was treated with methacrylated lignosulfonate solution. In particular, the flexural modulus and flexural strength more than doubled from 2.6 to 6.7 GPa and from 36 MPa to 76.8 MPa, respectively when the fibers were soaked in 5 wt % MLS solution. The SEM analysis revealed improved fiber-matrix interface and lower extent of fiber pull-out in the methacrylated lignosulfonate treated fiber composites, which correlates with the improved mechanical properties.

  • 34.
    Yandrapu, Sagar
    et al.
    National Institute of Technology, India.
    Gangineni, Pavan
    National Institute of Technology, India.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ray, Bankim
    National Institute of Technology, India.
    Prusty, Rajesh
    National Institute of Technology, India.
    Effects of electrophoretic deposition process parameters on the mechanical properties of graphene carboxyl-grafted carbon fiber reinforced polymer composite2020In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628Article in journal (Refereed)
    Abstract [en]

    Carbon fiber (CF) modification by grafting of various graphene-based nanofillers (GBN) by electrophoretic deposition (EPD) technique was proven to be a successful technique to enhance the out-of-plane performance of carbon fiber reinforced polymer (CFRP) composites. Graphene carboxyl (G-COOH) grafting on carbon fiber by electrophoretic deposition (EPD) is a promising technique to improve the mechanical properties of CFRP composites. To our knowledge, there is a dearth of literature available on the effect of EPD process parameters on the mechanical behavior of modified CFRP composites. The aim of this study is to evaluate the effect of nanofiller concentration in the suspension, applied current, and the time of deposition during EPD on the mechanical behavior of nanophase CFRP composites, thus making it a novel work. With increasing concentration, interlaminar shear strength (ILSS) improved consistently and has shown a maximum enhancement of 24.7% than that of neat CFRP composite at 1.5 g/L nanofiller concentration, whereas flexural strength remained almost unaffected with varying concentration. On the contrary, variation of deposition current has affected the flexural strength but not ILSS. The maximum flexural strength was obtained at a deposition current of 5.0A with an improvement of 16.3% in comparison with neat CFRP samples. However, both flexural strength and ILSS of hybrid CFRP composites have shown improvement with increasing deposition time. At 60 min of deposition, ILSS and flexural strength have shown maximum improvements of 35.0 and 26.6%, respectively, when compared to control specimen. After evaluating the effect of process parameters future scope of the work involves the optimization of parameters for EPD of G-COOH. Fractographic analysis of the fractured samples was performed using scanning electron microscope (SEM) to apprehend prominent failure mechanisms.

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