Changes in physical properties and molecular structure of butyl rubber during γ-irradiation

Abstract

Butyl rubber samples have been aged by γ-irradiation at 25°C in air. The change in molecular structure due to chain scission and formation of oxygenated groups also change the M ̄ n , tensile strength and density of butyl rubber. The rubber predominantly undergoes chain scission upon γ-irradiation up to a dose of 50 Mrad, but there is also substantial chain crosslinking above 50 Mrad. The yield G(x) has been found, which provides an insight into the mechanism of the radiolytic degradation. Hydroperoxide is the major product and unsaturation is incorporated in the polymer back bone. The change in molecular structure due to recombination and chain scission are followed by the formation of a more ordered structure and hence an increase in density.