Accelerated Heat Ageing and Life Prediction of Nitrile Rubber Vulcanizates

摘要

Elastomeric materials are commonly used for long-term applications either at room temperatures or at elevated temperatures. In this present work, accelerated heat ageing of Nitrile rubber vulcaniztes with and without antioxidants were carried out by using a hot air oven at temperatures 70, 90 and 100°C and for total time duration of 49 days. The mechanical properties such as tensile strength, elongation at break and modulus were measured before and after ageing. The tensile strength and elongation at break were found to decrease on increase in temperature and time duration. Morphology of both unaged and aged vulcanizates was measured to analyze the change in surface behavior of the rubber vulcanizates by using scanning electron microscopy. Swelling measurements were also carried out using solvent methyl ethyl ketone to measure the swelling index and cross-link density for both unaged and aged vulcanizates. The cross-link density was calculated by using Flory-Rehner equation to analyze the change in network structure after ageing. The percentage elongation at break was used as a critical parameter in Arrhenius equation to calculate the service life prediction of rubber vulcanizates.