Diffusion behavior of vitamin-E in irradiation cross-linked GO/UHMWPE composites

Graphene oxide/ultra-high molecular weight polyethylene (GO/UHMWPE) composite was prepared by hot pressing and irradiation cross-linked by γ-ray. Vitamin-E (VE) solution was diffused into matrix and homogenize treated to study the diffusion behavior. Weight change, diffusion depth and VE index after VE diffusion were studied. The results show that after VE soaking, the weight change is, however, not obvious at low temperature (80 °C and 100 °C), while apparent at 120 °C. Furthermore, the weight change of UHMWPE is most, while least of irradiation cross-linked GO/UHMWPE. GO filling and irradiation cross-linking had no significant effect on the molecular structure of UHMWPE, the characteristic peaks of VE can be clearly seen in the FT-IR. The diffusion depth of VE in UHMWPE is the largest, which is 280 μm. On the contrary, the shallowest diffusion depth of 70 μm in composites modified by GO and irradiation. The cross-linking degree caused by irradiation and larger two-dimensional structure of GO hindering VE diffusion, more soaking time and temperature are required to provide greater activation energy to obtain desired thickness. Besides, diffusion equation also established as a function of time and temperature based on Fickian theory, which is conducive to predict the diffusion depth of VE into UHMWPE matrix composite for targeted modification. Furthermore, diffusion mechanisms of VE also illustrated.