MECHANICAL, MOISTURE ABSORPTION AND DURABILITY CHARACTERIZATION OF PLA COMPOSITES REINFORCED WITH NANO-COATED FLAX FIBERS

摘要

This research is intended to improve the interface between the fibers and the matrix and limit water absorption of bio-based material thereby decreasing degradation of the composites when they are exposed to external environment such as high temperature and humidity. Flax fibers were treated with an organic surface coating containing silicon dioxide (SiO2) nanoparticles. This coating was a dispersion of silica fume in epoxy. Flax fibers/Polylactic acid (PLA) composites were manufactured by hot pressing of PLA films and flax fabrics. Morphology and dispersion of the coating on the fibers was observed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Accelerated ageing was carried out by placing different composites in a 50℃ water bath until saturation to investigate the influence of the coating on water diffusion. Mechanical properties were investigated by tensile (before and after conditioning) and short beam shear (SBS) testing in order to evaluate the impact of the coating on the interfacial properties. The results show that the fibers surface was homogenized and that a better adhesion was reached because of the coating. Coating the fibers also allowed the decrease in water uptake by more than 10% and their protection during conditioning, preserving their mechanical properties.