The effects of chemical change during sample preparation and low molecular weight chains of low density polyethylene (LDPE) have been investigated 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 terephthalate backing films were found to contribute to the increase of heterocharge in LDPE. All aspects of the processes used for the preparation of samples must be studied carefully to ascertain possible effects on the properties of samples. The type of charge accumulated in LDPE was also found to depend on the concentration of short PE chains. Details of experimental results and their possible causes are described.