The effects of gamma irradiation on RTV polysiloxane foams

The present work involves the investigation of ionizing radiation effects on silica filled poly (dimethyl siloxane) foam vulcanized at room temperature. In order to better predict aging effects in these materials, it is important to understand the influence of irradiation on structural-rheological property relationships. Polysiloxane foams were subjected to moderate doses of gamma irradiation in an inert atmosphere and characterized by thermal (DSC and TGA), chemical (FT-IR, NMR, Mossbauer, mass spectroscopy, EPR, solvent swelling), microscopy (SEM and AFM), and mechanical (uniaxial compressive load) techniques. Radiation exposure induced cross-linking reactions that predominated over chain scission reactions for the dose range investigated. No long-lived radiation-induced radicals were detected and the porous structure of the irradiated foam remained unchanged. Radiation exposure resulted in gas evolution, decrease in crystallization levels, slight changes in chemistry, and decrease in the molecular weight between cross-links, thereby hardening the foam.