Curing systems for rubbers used at low temperatures

This work is devoted to studying the properties of rubbers based on a blend of frost-resistant and oil-resistant rubbers. The vulcanizing group also includes vulcanization activators, including a complex sulfur vulcanization activator, which is an organo-mineral composition of zinc oxide, stearic acid, and a mineral carrier. The kinetic features of the formation of the spatial network of a vulcanizate consisting of a blend of heteropolar diene rubbers vulcanized with sulfur and thiazole accelerators and their combination with diphenylguanidine are studied. Based on the glass transition temperatures of the vulcanizates of the studied rubber blends, calculations were performed and sulfur distribution coefficients in the vulcanizates were determined. Analysis of the results revealed a discrepancy between the chemical activity of the rubbers and the data on sulfur binding by these rubbers in their combinations. A hypothesis is made that relaxation factors influence the rate of sulfur addition to macromolecules. During vulcanization, the chain relaxation rate of the studied rubbers is consistent with the degree of sulfur addition to the rubbers in their blends. However, it is inconsistent with the vulcanization activity of individual rubbers. This occurs because more mobile rubber chains have time to react more times with the surface of the actual vulcanization agent. When developing formulations based on heteropolar (incompatible) rubbers, for example, for oil- and petrol-resistant products operated at low temperatures, the nature of sulfur distribution between the phases of the compatible polymers must be taken into account. This distribution may also depend on the type of vulcanization accelerator used. The feasibility of using a complex vulcanization activator in formulations based on rubber blends is demonstrated. This ensures an improvement in the vulcanization and elastic-strength properties of the rubbers.