Electrical Conduction and Chemical Structure of Insulating Polymers

Currents in various polymers were measured using both a corona electrode and an evaporated metal electrode. The former could usually inject more carriers into polymers than the latter. The current in PE was two or three orders of magnitude larger with the corona electrode than with the evaporated metal electrode and injected negative carriers made a greater contribution to the current than positive ones. On the other hand, injected positive carriers played an important role in the currents in PTFE, FEP, PFA, and ETFE. Similar polarity effects were observed in the surface potential decay characteristics for coronacharged polymers. The polarity of injected carriers which dominated the current changed from negative to positive as the degree of fluorination of a polymer increases. Electronegative fluorine atoms were considered to provide negative carrier traps and suppress the current due to negative carriers.