Thermal properties and combustibility of cross-linked XNBR/CSM blends

The article describes the measurement results of the thermal properties of cross-linked blends of carboxylated butadiene-acrylonitrile rubber (XNBR, Krynac X.7.50) and chlorosulfonated polyethylene (CSM, Hypalon 48) under inert gas (DSC, TG) and in air (derivatography). The blends were cross linked at a temperature of 150 °C by means of MgO in the presence of stearic acid. The thermal curves were interpreted from the point of view of phase transitions and chemical reactions of high-molecular components. It has been found that the polymers under investigation show a good compatibility resulting from the presence of both inter-polymeric covalent bonds and inter-polymeric ionic bridges containing magnesium ions that fulfill the role of chemical compatibilizer. The study has shown that XNBR/CSM blends belong to a group of polymeric materials that are self-extinguished in air. Their flammability, determined by OI and the combustion time in air, clearly depends on the cross-linking degree associated with the quantity of MgO incorporated into the blend of elastomers.