POLY(LACTIC ACID)/PHORMIUM TENAX COMPOSITES: MORPHOLOGY AND THERMO-MECHANICAL BEHAVIOUR

Composites of Phormium tenax fibers in a poly(lactic acid) matrix with fiber content of up to 40 wt%, produced by injection molding and twin screw compounding, were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and mechanical tests (static and dynamic). Thermal analysis showed that cold-crystallization peak shifted to lower temperatures with increasing fiber content, confirming that the addition of Phormium fiber has the effect of promoting crystallinity. Dynamic mechanical analysis (DMA) results showed that the addition of Phormium fiber did not affect significantly the T-g of the polymer and the area under the tan delta decreased with the addition of Phormium fiber. Tensile modulus has been consistently increased by reinforcing the composite with growing amounts of fibers, whilst the effect on tensile strength is less evident. SEM micrographs of fracture surfaces allowed highlighting failure modes of the composites, which included a diffuse presence of fiber pull-out and debonding.