Environmentally friendly approaches for tailoring interfacial adhesion and mechanical performance of biocomposites based on poly(lactic acid)/rice straw.

Abstract

In the present research, plant-based biocomposites containing poly(lactic acid) (PLA) and rice straw (RS) as an annually renewable agricultural waste were studied. To enhance the properties of these filled systems, two environmentally friendly pulping methods were applied to remove the non-cellulosic components of RS and fibrillate the fibers. In addition, two reactive compatibilizers based on functional epoxy and maleic anhydride groups were incorporated into the biocomposites, using a reactive extrusion process. By pulping the RS fibers and modifying the PLA/lignocellulosic filler interface, the plant-based biocomposites with enhanced performance were attained. Furthermore, the elastic modulus, tensile strength, tensile toughness, impact strength, hardness, density and Vicat softening point of PLA and filled PLA system with untreated RS were improved. The impact resistance, tensile strength and elastic modulus of neat PLA were enhanced by 40 %, 160 % and 100 % for the modified biocomposites containing the environmentally friendly RS pulps. The obtained results showed that, these biocomposites had even higher mechanical performance than the PLA biocomposites containing RS pulp obtained through common soda-pulping method. The reasons behind these improvements are the partial pulping of RS, as well as the chain extension of PLA macromolecules and PLA grafting onto the lignocellulosic fiber surfaces induced by the reactive compatibilizers.