Investigations on mechanical properties of poly(propylene) and poly(lactic acid) reinforced by miscanthus fibers

Microscopic, nanoindentation and tensile tests were carried out to determine the mechanical behavior of PP and PLLA/reed fiber composites. As a first step, nanoindentation investigations were carried out to obtain longitudinal modulus and hardness of vegetal fibers. This study has allowed us to place the mechanical properties of reed fibers between those of sisal and hemp fibers. Optical microscopic observations have exposed the short length and the poor aspect ratio of the reed fibers used. Complementary SEM pictures have shown an improvement of the bonding between fibers and matrix with the addition of PP-g-MA or PLA-g-MA and the poor dispersion of reed fiber into composites by showing an important number of bundles. Tensile tests have highlighted an important improvement of the tensile modulus and a decrease of the tensile strength at yield with the addition of vegetal fibers. The presence of maleated matrix induces an improvement of modulus and strength for PP/reed composites. (C) 2008 Elsevier Ltd. All rights reserved.