Short noteConstitutive modeling of radiation effects on the permanent set in a silicone elastomer

When a networked polymeric composite under high stress is subjected to irradiation, the resulting chemical changes like chain scissioning and crosslink formation can lead to permanent set and altered elastic modulus. Using a commercial silicone elastomer as a specific example we show that a simple 2-stage Tobolsky model in conjunction with Fricker's stress transfer function can quantitatively reproduce all experimental data as a function of radiation dosage and the static strain at which radiation is turned on, including permanent set, stress-strain response, and net crosslink density.