Insight into the stabilization activity of n-SiO2 powder in SEBS phase

Abstract

The inhibition effects of silica nanoparticles on the styrene–ethylene–butadiene–styrene copolymer are investigated by chemiluminescence under an advanced degradation stage achieved by γ-irradiation at 50 kGy. The CL thermal and nonisothermal spectra reveal an improving stabilization activity as the silica loading increases from 2 and 5 up to 10 mass%. The greater the filler concentration is investigated, the higher stability is achieved. The values of activation energies emphasize the contribution of this filler on the delay of oxidation even in the irradiated matrices. The comparison of oxidation induction times obtained by isothermal chemiluminescence at 210 °C is a relevant proof for the action of superficial traps in the breaking down the auto-oxidation chain by means of the scavenging free polymer fragments. The values of activation energies required for the delay of oxidation increase from 85 kJ mol⁻¹ for pristine polymer to 100–124 kJ mol⁻¹ for composited SEBS in unirradiated states and from 58 to 91–103 kJ mol⁻¹ for these materials subjected to an accelerated oxidation by γ-irradiation at 50 kGy.