Mechanical and Moisture Absorption Characterization of PLA Composites Reinforced with Nano-coated Flax Fibers

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. In this study, flax fibers were treated with an organic surface coating containing SiO2 nanoparticles. This coating was a dispersion of silica fume in epoxy. One composite was also made with raw fibers as reference as well as one sample of pure PLA. Flax fibers/PLA composites were manufactured by hot pressing by stacking 4 PLA films and 3 pieces of flax fabric. Morphology and dispersion of the coating on the fibers was observed by scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Accelerated ageing was carried out on the 3 materials by placing them in a 50 degrees C water bath until saturation to investigate the influence of the coating on water diffusion. Mechanical properties of the different composites 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 of the materials. 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.

这项研究旨在改善纤维与基质之间的界面并限制基于生物的材料的吸水，从而在暴露于外部环境（例如高温和湿度）时减少复合材料的降解。在这项研究中，亚麻纤维用含有SIO2纳米颗粒的有机表面涂层处理。这种涂层是环氧树脂中二氧化硅烟的分散。还用原始纤维作为参考和一个纯PLA样品制成了一种复合材料。亚麻纤维/PLA复合材料是通过堆叠4个PLA膜和3片亚麻织物来制造的。通过扫描电子显微镜（SEM），小角度X射线散射（SAXS）和透射电子显微镜（TEM）观察到涂层在纤维上的形态和分散。通过将其放入50摄氏度的水浴中，直到饱和以研究涂层对水扩散的影响，从而在3种材料上进行加速老化。通过拉伸（条件前后）和短束剪切（SBS）测试研究了不同复合材料的机械性能，以评估涂层对材料界面特性的影响。结果表明，纤维表面是匀浆，并且由于涂层而达到了更好的粘附。涂层纤维还可以减少水吸收超过10％，并在调节过程中保护其机械性能。