The Fracture Behavior of Rubbery Vulcanizates: I. Single Component Versus Blend Systems

The tear energy and heat build up of NR, SBR and BR vulcanizates and their corresponding blends were measured at several temperatures via modified trouser tear and Goodrich flexometer experiments. In all single component samples, by increasing temperature from -10 to 125 °C, the fracture energy decreases, goes through a minimum and increases again. Nevertheless, in SBR and BR, a level off and a level off followed by second drop occur at higher temperatures, respectively. On the other hand, for aforementioned samples the heat build up decreases monotonically by raising the temperature. For two-component blends, the fracture energy and heat build up show different dependencies on temperature in comparison to single component systems. The fracture energy either increases, does not change at first and then decreases, or does not change as the temperature increases. While the heat build up is more or less constant by raising the temperature up to a certain point and then decreases but by a different path from single component vulcanizates. These peculiar behaviors are attributed to the competition between residual stress release and reduction of viscose loss term, while the temperature increases.