Melt extruded polylactic acid (PLA)/algae bio-composites: Effect of grafting level and filler loading on thermal and mechanical properties

In this study, the combined effect of algae loading and in-house produced coupling agent on thermal and mechanical properties of polylactic acid (PLA) prepared by melt compounding were investigated. The PLA-grafted with maleic anhydride (MA) (PLA-g-MA) was used as a coupling agent to improve the interfacial adhesion between PLA and algae. The extent of grafting level was confirmed with FTIR and direct titration method. The results demonstrated the dependence of thermal stability and tensile properties on the grafting level of MA, and also on the concentrations of algae. Thus, it could be deduced that combination of algae at low concentrations (5 and 10 wt%) and PLA-g-MA with high grafting level can significantly improve the thermal stability of PLA. High grafting level of MA, showed increase in thermal stability of PLA. On the other hand, at high grafting level, there was an improvement in tensile modulus of PLA. The morphological analysis indicated better adhesion between algae and PLA, in composites containing PLA-g-MA with high grafting level. Overall, PLA/algae composites with improved interfacial adhesion and thermal stability were successfully prepared, in the presence of PLA-g-MA with high grafting level.