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  • 1.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Bakare, Fatimat
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Bio-based thermoset resins from soybean and linseed oils for structural composites2011Conference paper (Refereed)
  • 2.
    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.

  • 3.
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Development of biocomposites from lactic acid thermoset resins and cellulose fibre reinforcements2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Synthesis of polymers from renewable origin has been reported by many authors and it has been found out that it has enormous potential and can serve as alternative to conventional thermoplastics and thermosets in many applications. The use of these renewable resources will provide sustainable platforms to substitute fossil fuel-based materials. To date, efforts made to produce 100% bio-based thermosetting materials have yet to be achieved. Many studies have been reported on increasing the renewability ratio of thermoset materials produced.

    A lot of reports have been made on the synthesis of thermoplastic resins from lactic acid for biomedical applications such as tissue engineering but only few reports have been made on composite applications. The issue of high melt viscosity of thermoplastic resins from lactic acid has been of paramount problem because of its difficulty in impregnation into fibre reinforcement. Bio-based thermoset resins have been produced for composite applications from plant oils and improved mechanical properties have been achieved.

    In this thesis, an alternative route for synthesis of lactic acid based thermoset resins have been explored to solve the above problem. Thermoset resins were synthesized from lactic acid with different co-reactants and were characterized using NMR, FT-IR, DSC, DMA and TGA. Their rheological properties were also investigated. The resins were reinforced with natural and regenerated cellulose fibres in non-woven and woven form, and with different fibre alignment and fibre loading. The resulting composites were characterized by mechanical testing regarding tensile, flexural and impact strength, and by SEM analysis regarding morphology.

    The results showed that these composites could possibly be used in automobile, transport, construction and furniture applications, particularly for interior purposes. The resins produced were found to be promising materials for composite production due to the good mechanical properties achieved.

  • 4.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Wang, Yanfei
    Afshar, Shahrzad Javanshir
    Esmaeli, Nima
    Åkesson, Dan
    University of Borås, School of Engineering.
    Morphological and mechanical properties of a biobased composite from a lactic acid based thermoset resin and viscose fiber reinforcement2014Conference paper (Refereed)
  • 5.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Wang, Yanfei
    Afshar, Shahrzad Javanshir
    Esmaeli, Nima
    Åkesson, Dan
    University of Borås, School of Engineering.
    Synthesis and Preparation of Biobased Composites with A Novel Thermoset Resin from Lactic Acid2014Conference paper (Refereed)
  • 6.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Wang, Yanfei
    Afshar, Shahrzad Javanshir
    Esmaeili, Nima
    Synthesis and Characterization of Bio-Based Thermosetting Resins from Lactic Acid and Glycerol2014In: Journal of Applied Polymer Science, E-ISSN 1097-4628, Vol. 131, no 12, p. 1-9Article in journal (Refereed)
    Abstract [en]

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

  • 7.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Wang, Yanfei
    Esmaeili, Nima
    Afshar, Shahrzad Javanshir
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Biobased Composites Prepared From a Lactic Acid Based Thermoset Resin and Natural-Fiber Reinforcement2013Conference paper (Refereed)
  • 8.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Wang, Yanfei
    Esmaeili, Nima
    Afshar, Shahrzad Javanshir
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    The Effect of Glycerol in the Synthesis of a Lactic Acid Based Thermoset Resin2013Conference paper (Other academic)
  • 9.
    Bakare, Fatimat Oluwatoyin
    et al.
    University of Borås, School of Engineering.
    Wang, Yanfei
    Esmaeili, Nima
    Afshar, Shahrzad Javanshir
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    The Effect of Glycerol in the Synthesis of a Lactic Acid Based Thermoset Resin2013Conference paper (Refereed)
  • 10.
    Bakare, Fatimat
    et al.
    University of Borås, School of Engineering.
    Åkesson, Dan
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Bashir, Tariq
    University of Borås, School of Engineering.
    Ingman, Petri
    Srivastava, Rajiv
    Synthesis and characterization of unsaturated lactic acid based thermoset bio-resins2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, p. 570-582Article in journal (Refereed)
    Abstract [en]

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

  • 11.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Bakare, Fatimat
    University of Borås, School of Engineering.
    Baghaei, Behnaz
    University of Borås, School of Engineering.
    Mehrjerdi, Adib Kalantar
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Influence of different organic solvents and oxidants on insulating and film-forming properties of PEDOT polymer2013In: Iranian polymer journal, ISSN 1026-1265, E-ISSN 1735-5265, Vol. 22, no 8, p. 599-611Article in journal (Refereed)
    Abstract [en]

    Processing of conjugate polymers has always been a challenge because of their poor solubility and infusibility in organic and inorganic solvents. The processibility and applications of intrinsically conductive polymers (ICPs) can be enhanced by producing their solutions or dispersions in different suitable solvents. It can also be achieved by preparing un-doped or electrically neutral polymers, which can further be transformed in semiconductor after oxidation/reduction reaction. The present study focuses on the preparation of active dispersions of poly (3,4-ethylenedioxythiophene) (PEDOT) conductive polymer in various organic solvents. For this purpose, the polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer was carried out in three different organic solvents, ethanol, 1-butanol and acetonitrile with two commonly used oxidants, ferric (III) chloride (FeCl3) and ferric (III) p-toluenesulfonate (FepTS). In this regard, the oxidant and monomer solutions with variable molar concentrations (0.25, 0.5, 1.0 M) were prepared in particular solvents and then these solutions were mixed with different monomer/oxidant volume ratios. The obtained dispersions of PEDOT can readily be polymerized on the surface of different materials after solvent evaporation and a uniform film can be achieved. The effect of molar as well as volume concentrations of EDOT monomer and oxidant on insulating (undoped/neutral) and film forming properties of PEDOT was investigated. These dispersions were applied on a transparent PET film and cellulosic fibers (viscose), dried at room temperature and analyzed using scanning electron microscope (SEM), optical microscope and ATR-FTIR spectroscopic analysis. The electrical characterization of undoped PEDOT-coated fibers was performed on Keithly picoammeter. This study contributes to obtain a simpler and instantaneous polymerization method of PEDOT preparation and to enhance its application area.

  • 12. Esmaeli, Nima
    et al.
    Bakare, Fatimat Oluwatoyin
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Afshar, Shahrzad Javanshir
    Åkesson, Dan
    University of Borås, School of Engineering.
    Mechanical properties for bio-based thermoset composites made from lactic acid, glycerol and viscose fibers2014In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 603-613Article in journal (Refereed)
    Abstract [en]

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

  • 13.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat
    University of Borås, Faculty of Textiles, Engineering and Business.
    Herrmann, Rene
    Arcada University of Applied Science.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

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

  • 14.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical and thermal properties of the textile bio-composites: measurement and prediction2015In: , 2015Conference paper (Refereed)
  • 15.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bashir, Tariq
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ingman, Petri
    University of Turku.
    Srivastava, Rajiv
    Indian Institute of Technology Delhi.
    Synthesis and characterisation of unsaturated lactic acid based thermoset bio-resins2015In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, no June 2015, p. 570-582Article in journal (Refereed)
  • 16.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Esmaeili, Nima
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Afshar, Shahrzad
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical properties for bio-based thermoset composites made from lactic acid, glycerol and viscose fibers2015In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 603-613Article in journal (Refereed)
1 - 16 of 16
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