USE OF GROUP IVB METAL-OXIDES FOR CURING POLYACRYLIC RUBBER

Group IVB metal oxides, both with and without ethylene thiourea (ETU) have been used to cure polyacrylic rubber (ACM). Curing characteristic s and properties of the vulcanizates have been studied with a view to elucidate curing mechanism with special reference to the role of metal oxides (e.g. SnO, SnO2, PbO, PbO2 and Pb3O4). Best results are obtain ed with Pb3O4, in the presence of ETU and with SnO in the absence of E TU. PbO-SnO or PbO2-SnO blends provide no synergistic effect. In the p resence of ETU, the formation of metal sulphide and metal chloride in the vulcanizate is confirmed by XRD and XPS. Studies on IR spectra sho w that crosslink occurs at the C-Cl cure site of the polymer. Based on the experimental results a mechanistic reaction scheme has been put f orward.