Ultra-high molecular weight polyethylene (UHMWPE) is a unique high performance polymer with outstanding mechanical properties and low density. However, the critical disadvantage of UHMWPE is its low thermal stability which can be improved by polymer crosslinking. The photocrosslinking was carried out by continuous UV irradiation on UHMWPE films containing a hydrogen-abstractable photoinitiator. The UHMWPE films were prepared by high temperature compression molding of UHMWPE powder dispersed with a photoinitiator. The photoinitiator addition increased the gel fraction of the irradiated UHMWPE up to 99%. The photocrosslinking was attributed to the recombination of the polymer radicals which was generated by the hydrogen abstraction of the UHMWPE polymer chains by the excited photoinitiator under UV irradiation. Also the crosslinked UHMWPE films showed higher thermal stability such as reduced enthalpy of fusion and enhanced thermal decomposition temperature with increasing UV energy as observed by DSC and TGA.
Effect of photocrosslinking on the thermal stability of UHMWPE films