Effect of curatives and fillers on vulcanization, mechanical, heat aging, and dynamic properties of silicone rubber and fluororubber blends

The cure characteristics and mechanical properties of gum and filled silicone rubber (MVQ), fluororubber (FKM), and MVQ-FKM blends with different compositions were investigated before and after aging. The rheometric study showed that optimum cure properties were obtained using the curing system of dicumyl peroxide (DCP) and triallylisocyanurate (TAIC). From varying the curing agents, the optimum levels of DCP and TAIC were found to be 2.0 phr and 1.5 phr, respectively. The addition of different fillers and their loading influenced the cure behaviors, with increased torque and scorch time compared with that of gum blends. The filled 50:50 (w/w) MVQ-FKM blends showed overall performance in mechanical properties. Post-curing improved the strength of MVQ-FKM blends, especially the blends with a higher proportion of FKM. Swelling of the blends was reduced with the addition of fillers and the increased incorporation of FKM. Dynamic mechanical analysis showed two tan delta peaks corresponding to MVQ and FKM phase for filled blends, respectively. The storage modulus of the blends increased with the addition of fumed silica, indicating the presence of polymer-filler interaction.