Reinforced Flax Mat/Modified Polylactide (PLA) Composites: Impact, Thermal, and Mechanical Properties

Polylactide (PLA)/flax mat and modified PLA/flax mat composites were produced by the hot pressing technique. The dispersion of the flax mat in the composites was studied by the scanning electron microscopy (SEM). The PLA composites were subjected to an instrumented falling-weight impact test. The mechanical and thermal properties of the composites were determined by using tensile tests, a thermogravimetric analysis (TGA), and a dynamic-mechanical thermal analysis (DMTA). It was found that the flat mat increased the impact resistance of PLA, but the tensile strength of the modified PLA/flax mat composite decreased slightly compared with that of PLA. Data on the elongation at break pointed to a higher ductility of the modified PLA and its composites. Moreover, the addition of a thermal modifier enhanced the thermal resistance below the processing temperature of PLA and had a marginal effect on its glass-transition temperature. The master curves of the storage modulus were constructed by employing the time-temperature superposition (TTS) principle. The principle of a linear viscoelastic material was fairly applicable to transition from the modulus to the creep compliance for all the systems studied.