Effect of Thermal Cycling on D.C. Conductivity and Morphology of Polyethylene

Abstract

Abstract The effects of long period repeated thermal cycling in the presence of d.c. electric field on the d.c. conductivity, morphology and degree of crystallinity of low density polyethylene (LDPE) were investigated. D.C. conductivity measurements indicate that a reasonable steady state conductivity could be achieved after a period of 10 days of thermal cycling between 80°C and 40°C in the presence of a d.c. electric field across the sample followed by another 10 days of conductivity measurements at constant temperature of 80°C. Crystallinity evaluation as well as morphological investigations using scanning electron microscopy (SEM) of etched surfaces of the material before and after thermal cycling and conductivity measurements show that the investigated material has undergone structural changes after that long period of thermal cycling and conductivity measurements. An attempt is made to correlate between the d.c. conductivity results and the observed structural changes in the material.