EFFECTS OF SAMPLE PREPARATION CONDITIONS AND SHORT CHAINS ON SPACE-CHARGE FORMATION IN LDPE

The effects of chemical change during sample preparation and low molec ular weight chains of low density polyethylene (LDPE) have been invest igated in order to clarify the origins for heterocharge in LDPE which does not contain antioxidants. The carbonyls formed at the surface of polyethylene (PE) sheet prepared at 180 degrees C with polyethylene te rephthalate backing films were found to contribute to the increase of heterocharge in LDPE. All aspects of the processes used for the prepar ation of samples must be studied carefully to ascertain possible effec ts on the properties of samples. The type of charge accumulated in LDP E was also found to depend on the concentration of short PE chains. De tails of experimental results and their possible causes are described.