Effect of Vinyl and Phenyl Contents of Silicone Gum on the Properties of the Elastomers and Cellular Silicone Cushions

摘要

Two series of random terpolymers of dimethyl-diphenyl-methylvinylsiloxane were synthesized. In one series, the amount of methylvinylsiloxane was varied from 0 to 5 wt % and diphenylsiloxane was maintained at a nominal 12 wt %. In the other series, diphenylsiloxane was varied from 0 to 18 wt % and methylvinylsiloxane was maintained at a nominal 1 wt %. Molecular weights were maintained around 500,000. These gums were filled with about 26 wt % silicon dioxide and then converted to the intermediate elastomers, temporarily filled molding compounds, and cellular silicone cushions. The intermediate elastomers and cellular silicones were cured with a vinyl specific catalyst and tested. Increasing vinyl content increases the stiffness of the cushion but decreases its resiliency. Compression set reaches a minimum of about 5% at a methylvinylsiloxane content of about 0.9 wt %. Phenyl content has only a slight effect on cushion properties. Compression set is a minimum in a range of 7 to 14 wt % diphenylsiloxane. (ERA citation 06:017132)