Poly(lactic acid) reinforced with synthetic polymer fibers: interactions, structure and properties

Poly(lactic acid) (PLA) was modified by the addition of synthetic polymer fibers, poly(ethylene terephthalate) (PET) and poly(vinyl alcohol) (PVA) to improve its stiffness and impact resistance. Wood flour was used as reference in the study. The results showed that polymer fibers improve stiffness moderately and impact strength considerably compared to wood flour. Local processes strongly influence the performance of the materials. Plastic deformation initiated by debonding results in large impact resistance, while fiber fracture leads to efficient reinforcement. Coupling has only a minor effect on local processes and properties, since PET fibers have functional groups capable of chemical bonding only the end of their chains, on the one hand, and because of the large number of hydroxyl groups resulting in strong adhesion between PLA and the other two reinforcing agents, wood flour and PVA, on the other. The property combination achieved by PLA/PVA fiber composites is beneficial for engineering applications.