Influence of the technological mode of mixing and curing system on the properties of compositions based on nitrile rubber and ultrahigh molecular weight polyethylene

The results of a study of the influence of the mixing mode and curing system on the properties of low temperature and oil resistant rubber based on a composition of butadiene-nitrile rubber (BNKS-18AMN) and ultra-high molecular weight polyethylene (GUR 4113) are presented. Different ways of UHMWPE introducing into the rubber compound are considered: mixing before and after the introduction the main ingredients of the rubber compound at temperatures up to 80 °C (below the melting point of UHMWPE) and preliminary high-temperature (160 °C) mixing of rubber and UHMWPE. It was found that the preliminary high temperature mixing of rubber with UHMWPE leads to a decrease in the viscosity of the rubber compound, as well as a reduction in the scorch time and the achievement of an optimum vulcanization but does not lead to significant changes in the physical and mechanical properties and oil resistance of vulcanizates. The study of the influence of the curing system showed the effectiveness of using a combined sulfur-peroxide curing system, which is manifested in the improvement of the technical properties of vulcanizates, which is largely due to an increase in the density of rubber crosslinking through the formation of stronger and more heat-resistant C-C bonds. It has been shown that the best set of technical properties of vulcanizates, including high frost-resistance, physical and mechanical properties, resistance to hydrocarbon environment and retention of properties after thermal exposure, is achieved when using the sulfur-peroxide combination S/DCP – 1/2.