| Time-temperature dependent mechanical properties of three different elastomeric networks containing C-C covalent, ionic, and mixed crosslinks have been studied. Styrene-butadiene rubber (SBR) and carboxylate SBR were mixed with dicumylperoxide (dicup) and zinc oxide (ZnO) to give C-C covalent crosslinks (CC) and ionic crosslinks (IC), respectively. Dicup and ZnO were used together to form mixed crosslinks (MC).;The crosslink density of CC and IC vulcanizates is similar; the MC had a slightly higher value. IC showed a tan ;However, tensile and tear properties of IC decreased rapidly with increasing temperature and decreasing strain rate, such that under these conditions CC exhibited superior strength relative to IC. With mixed crosslinks, strength fell between that of IC and CC at low temperature, while at the highest temperatures, vulcanizates with mixed crosslinks showed the best strength. |
