Effect of surface oxidation on space charge characteristics of LDPE films

Published in 2015

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Summary

In this study, effect of surface oxidation on space charge characteristics of low density polyethylene films (LDPE) has been investigated. LDPE particles were dried for 12 hours at 60 oC and prepared into films with thicknesses of about 0.23mm by hot press method. Then the LDPE films were oxidized for different times in ozone atmosphere. Infrared (IR) spectroscopy was used to characterize the change of surface chemical composition. The results indicated that carbonyl (C=O) has been incorporated into LDPE surface layers, and the absorption strength of C=O enhanced with increase of oxidation time. Scanning electron microscope (SEM) was conducted to observe the variation of surface morphology of specimens before and after oxidation. SEM results show that surface oxidation can lead to the deposition of LDPE surface, because some cracks and holes appeared after oxidation treatment. Finally, space charge distributions of specimens were measured by pulsed electro acoustic (PEA) method. The PEA measurements results show that oxidation can lead to a large number of heterocharges accumulate in the vicinity of electrodes, especially for the positive charge near the cathode. The total amount of space charges in the bulk of specimens presents an increasing trend with increase of oxidation time. The change of charge injection characteristics and accumulation characteristics were considered to be caused by the variation of trap parameters, which needed to be further investigation.