AGING OF VULCANIZATES OF FORMULATIONS FOR RUBBER SEALS

Typical formulations based on NBR (acrylonitrile butadiene rubber), EP DM (ethylene propylene diene monomer rubber), and a NBR-CR (polychloro prene rubber) blend were studied for various properties under accelera ted air aging conditions. The trend in tensile properties indicated th e propensity of these formulations to oxidative degradation. The deriv atives of these properties, such as their retention indices, strain en ergy, and Mooney-Rivlin constants also showed similar trends. Some of the observations correlate to shelf-aging data, but the time to ruptur e data derived from ultimate elongation values did not provide tangibl e conclusions. (C) 1998 John Wiley & Sons, Inc.