Eco Friendly Composites Prepared from Lactic Acid Based Resin and Natural Fiber

University essay from Högskolan i Borås/Institutionen Ingenjörshögskolan; Högskolan i Borås/Institutionen Ingenjörshögskolan

Abstract: Lactic acid based thermoset were synthesised by reacting lactic acid with glycerol andfunctionalizing lactic acid branches by methacrylic anhydride. Resins with different chainlength were prepared and their thermo mechanical properties were examined through DMAanalysis and their molecular structures were analyzed by NMR method and their viscositywere investigated through rheometry analysis and three monomers were selected as the bestchain length. Degree of reaction in different reaction times was evaluated by a modifiedtitration method and bulk preparation of resin was performed by optimal process condition.DSC analysis was conducted in order to evaluate curing behaviour of resin with benzoylperoxide as cross-linking initiator. TGA analysis was performed to check thermo stability ofthe resin. Bio composites by viscose unidirectional and bidirectional knitted fabrics and alsonon woven viscose fiber with different fiber loads were prepared by ordinary hand layupimpregnation followed by compress moulding and their mechanical and thermo mechanicalproperties were characterized by tensile, flexural, charpy and DMA analysis and optimumfiber loads were identified for each fiber type. Ageing properties of prepared composites wereexamined by placing samples in climate chamber to simulate long time ageing and ageingexperiment was followed by tensile and flexural test to evaluate mechanical properties afterageing simulation. Composite`s swelling properties for water and some other solvents wereinvestigated and also their chemical resistance were evaluated by immersing them in 1M HCland KOH. The resin was also compared with a commercial oil based thermoset by preparingglass fiber reinforced composites and also effect of adding styrene to the resin were evaluated.Results of this work demonstrated that the novel synthesised have very high mechanical andthermo mechanical properties surpassing commercial oil based poly esters but ageingbehaviour is not very good however adding styrene can improve ageing properties. Also theresin is compatible with cellulosic natural fibers and forms strong composites.

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