Degradation of polyethylene by combination of thermal aging and radiation

A 25 µm thick low density polyethylene film free from additives had been subjected to γ-irradiation with a dose rate of ca. 5.3×10⁴ rad/hr at room temperature in air (denoted as γ) and/or thermal aging at 90 °C in air (denoted as HT). The order of oxidative degradation is (γ)≤(HT−γ)<(γ −HT)≃((γ,HT)), where () means the single or sequential application of γ and HT, the bar means the order of the application of them and ((γ,HT)) means the simultaneous application of γ and HT.