Effects of hygrothermal conditions and UV radiation on UHMWPE Fibers/Nanofiber-Epoxy composites

Nanofiber-epoxy with reactive graphitic nanofibers (r-GNFs) showed an improvement in adhesion properties in ultra-high molecular weight polyethylene (UHMWPE) fibers/epoxy resin composite (bundle/tow form) in our previous experiments. In this study, moisture absorption characteristics of pure-epoxy, nanofiber-epoxy materials and their UHMWPE bundle composites were investigated under hygrothermal aging and UV conditions. For the matrix specimens the weight gain deviated from Fick's law, and thus, a two-stage model, which includes both diffusion and structural relaxation, was applied to analyze the moisture absorption behaviors. For the bundle composites the results indicated that the weight gain showed compatibility with Fick's law. The UHMWPE fiber composite with nanofiber- epoxy containing 0.3wt% r-GNF loading resulted in the lowest rate of water absorption. Bundle composites were also exposed to accelerated UV aging conditions. The UV test results showed that the plateau stress and ultimate tensile strength of the bundle composites have been reduced. However, the ductility of the UHMWPE composites was increased due to the plasticization in hygrothermal aging tests.