Investigations on Low Temperature Transitions and Time Effects of Branched Polyethylene by the Positron Lifetime Technique

Abstract

Positron lifetime measurements are performed in branched polyethylene in the temperature range between -195 and +40 °C. The lifetime spectra are r esolved into four components, and corresponding annihilation mechanisms are discussed. Within the temperature range mentioned above four different transitions at -1 45, -95, -58, and -13 °C can be observed. From the behaviour of the lifetime parameters of the longest-lived component it is possible to deduce a criterion for the glass t ransition, which is situated at -13 °C. Additionally, time effects of the lifetime parameters are detected.