CONDUCTION MECHANISMS AND HIGH-FIELD EFFECTS IN SYNTHETIC INSULATING POLYMERS

The absorption and conduction currents in synthetic insulating polymer s, viz., polyethylene, polypropylene, polyethylene-terephthalate and p olyvinylidenefluoride, with dc fields may be electronic or ionic both and it may be difficult to determine their origins unambiguously. The charges which are present in the bulk of the polymer may be responsibl e for both the absorption and the conduction current. A limited displa cement of charges together with the rotation of side chains may provid e a decaying transient current in the presence of an externally impres sed field whereas the conduction current may originate from a hopping of charge carriers in which the charges transfer between localized sta tes. The complex dielectric response of these polymers with ac field m ay also be explained by intra- and inter cluster charge movement which would be consistent with the unified model, stated above for the case of dc fields.