Influence of filler and cure systems on thermal aging resistance of natural rubber vulcanizates under strained condition

Aging and decomposition of polymer based articles are influenced by various environmental factors. Hence, it is important to research the various factors precisely to interpret the aging mechanism. This study deals with the tensile set properties of natural rubber (NR) vulcanizates with different reinforcing and cure systems after thermal aging. The tensile set increased with increasing both the aging temperature and aging period. Thermal aging resistance and tension set was enhanced by increasing the cure accelerator content in the sample. The carbon black-filled NR vulcanizates showed better thermal aging resistance than the silica-filled ones. It was found that silane coupling agent enhanced the thermal aging resistance of the silica-filled NR vulcanizates. The experimental results could be explained by the cross-link density change and also from the consumption of the antidegradants due to thermal aging. The permanent tension set and cross-link density were increased as the aging temperature and aging time were increased. The filler and cure systems were found to influence on the surface morphologies of the thermally aged samples. The cross-link density change was a key factor of the changes of tension set.