Cross-linking of unplasticised poly(vinyl chloride) with peroxide

The peroxide cross-linking of poly(vinyl chloride) (PVC) with trimethylolpropane trimethacrylate (TMPTMA) has been investigated. The degree of cross-linking was measured in terms of the gel content of the material, i.e. the insoluble residue remaining after soxhlet extraction in tetrahydrofuran. Cross-linking gave rise to significant improvements in high temperature tensile strength, but at higher levels of peroxide, dehydrochlorination of PVC was found to compete with grafting and cross-linking reactions. The results have been analysed to predict the optimum amount of TMPTMA and peroxide to maximise gel content and strength while maintaining thermal stability.