Radiation crosslinking of poly(vinyl chloride) with trimethylolpropane trimethacrylate. I. Dose dependence and the effects of thermal treatment

The radiation crosslinking of poly(vinyl chloride), PVC, with trimethylolpropane trimethacrylate, TMPTMA, has been examined. The polyfunctional TMPTMA undergoes rapid polymerization incorporating the PVC into a three-dimensional network. The kinetics and mechanism of these crosslinking reactions were studied with particular reference to dose dependence and thermal treatment. The gel was rapidly formed with a TMPTMA polymerization rate greater than that of the PVC grafting reaction. Only 30 to 40% of the available bonds were used in the initial polymerization. The remaining 60 to 70% of the double bonds predominantly react in the final stages of crosslinking (80 to 100% gelation). The macroscopic properties (e.g., solubility, glass transition temperatures, mechanical characteristics, etc.) of the PVC-TMPTMA blend are discussed in terms of the molecular crosslinking mechanisms. The effect of thermal treatment, during and after irradiation, on the reaction rates and mechanism is examined