Influence of Nanofiller on the Degradation and Aging Resistance of Hydrogenated Nitrile Butadiene Rubber

Studies on degradation of elastomers and their prevention have become increasingly important in recent years because the environmental conditions in many industrial applications have become more severe and specification limits have been tightened. It is well known that unsaturated elastomers degrade faster than its saturated counterpart. Even with the use of saturated elastomers degradation cannot be prevented. Degradation can take place chemically as well as mechanically, accelerated by various factors like heat, light , level of stress etc. Anti-degradants are normally used to prevent degradation. In our recent studies, nanofillers especially nanoclays have been found to prevent degradation significantly. Nanoclay - reinforced hydrogenated nitrile rubber vulcanizate was subjected to accelerated heat aging to estimate its long-term thermo-oxidative stability and its useful lifetime was compared with that of the virgin polymer. Changes in tensile strength, modulus and elongation at break were studied as a function of time and temperature of aging. Incorporation of nanoclay resulted in significant improvement of the degradation profile of the nanocomposite at elevated temperatures. Restricted degradation by the clay filled rubber prolonged the durability. It was found from the scanning electron microscopy and atomic force microscopy studies that nanofillers protected the elastomer from surface rupture during oxidation. Reactive Force Field (ReaxFF) molecular dynamics simulation was performed to understand thermal decomposition characteristics of the rubber in presence of the nanofiller . The initial decomposition temperature, the final degradation temperature and the rate of degradation improved to a great extent on addition of the nanofiller from the theoretical studies.