Positron Lifetime Investigations on Linear Polyethylene Compared to Branched Polyethylene

Abstract

Positron lifetime measurements on linear polyethylene are performed in the temperature range between -192 and + 180°C. The results are compared wi th works on branched polyethylene. The criterion for the glass transition given earlier is proved. Branched and linear polyethylene show the same transitions at approx imately the same temperatures. The only exception is the transition at -58°C found in branched polyethylene only. Most deviations between the results of the two polyethylene samples can be explained by the different number of branching points or different cristallinity. Time effects of the lifetime parameters below the glass transition are observed.