Thermoanalytical Methods in Vulcanizate Analysis I. Differential Scanning Calorimetry and the Heat of Vulcanization

Abstract

Abstract Our objective has been to demonstrate that DSC is a convenient and rapid technique for the study of elastomer vulcanization characteristics. Although we have been concerned only with NR and NR-BR blends, the observation of exothermicity in sulfur vulcanization is quite general. Similar observations on sulfur vulcanization of IIR, SBR, EPDM, CSM, and NBR rubbers have been made in our laboratory. In non-sulfur vulcanization systems, we have found the diurethane cure of natural rubber to be exothermic and amenable to DSC study. As reported by Bruce et al., the magnesium oxide cure of chloroprenes is exothermic, but magnesium oxide-diamine vulcanization of fluoroelastomers is characterized by very low exothermicity. Future studies of the effect of various additives on soft rubber cure could make a significant contribution to our understanding of the complex cure mechanism. Successful kinetic analysis of DSC scans is perhaps the major hurdle to be overcome before the DSC technique can be meaningfully applied to such problems.