Peroxide cross-linking of rigid PVC

The optimum conditions for crosslinking rigid PVC with trimethylolpropane trimethacrylate (TMPTMA) and peroxide have been examined. The extent of crosslinking was measured by determining gel content by Soxhlet extraction in tetrahydrofuran. Mechanical properties were measured at 130°C and dynamic viscoelastic measurements were carried out to detect changes in the glass transition temperature (Tg). It was found that 15phr of TMPTMA and 0.3 phr of peroxide were optimum concentrations for maximising the extent of crosslinking, tensile strength and Tg. The lower moulding temperature of 170°C was preferred to minimise thermal degradation.