The shape memory effect of crosslinked ultra-high-molecular-weight polyethylene prepared by silane-induced crosslinking method

Crosslinked ultra-high-molecular-weight polyethylene (UHMWPE) with excellent shape memory properties was prepared from the silane-grafted UHMWPE mixed with water-carrying agent by compression molding. The alkoxysilane hydrolyzation and condensation reaction of the silane-grafted UHMWPE allowed for the generation of Si–O–Si chemical crosslinking points between the polymeric chains. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results confirmed that silane has been grafted on UHMWPE chains successfully. The resulting crosslinked products were characterized using dynamic mechanical analysis, gel measurement, impact test, tensile test, thermogravimetric analysis and shape memory bending test to obtain insight into the relationship between the structure and the properties. By controlling the content of water-carrying agent, the average molecular weights between crosslinking points (M_c) reduced from 29,530 to 9540 g/mol. The decomposition temperature (T_d) value increases from 467.7 for virgin resin to 491.5 °C for the crosslinked product with 91.64% gel ratio. The crosslinked materials showed much better shape memory effect than pure UHMWPE; the shape recovery ratio (R_ν) value of silane-induced crosslinked UHMWPE with 1.0 phr water-carrying agent reaches above 98.0% under multiple deformation recovery cycle. Therefore, the silane-induced crosslinking UHMWPE has a great potential in the shape memory material applications.