A Quantitative Test for Ozone Resistance of Rubber Vulcanizates

Abstract

Abstract A simplified procedure was developed for evaluating ozone resistance of rubber vulcanizates in terms of critical stress—strain and stored energy density parameters. A selected tensile force of appropriate magnitude is applied to a tapered specimen to produce a continuous range of stress. While thus stretched, the specimen is conditioned for 16 h, then exposed to ozone for 24 h. In the portion of the specimen where the stress is greater than a critical value σc, ozone cracking occurs, whereas in the portion of the specimen where the stress is less than σc there are no cracks. Values of σc the critical strain εc, the critical elastic stored energy Wc, and the elastic modulus E are determined from the position of the boundary between the cracked and uncracked zones, the average elongation of the stressed specimen, and the specimen geometry. The quantity Wc was found suitable for quantitatively characterizing ozone resistance by a single parameter.