Electrical conduction in acrylonitrile/methylacrylate copolymer films

Electrical conduction phenomena on unstretched and stretched films of an acrylonitrile/methylacrylate copolymer were studied by isothermal and thermally stimulated charge decay measurements after corona charging in a wide range of field strengths and temperatures, including the glass transition temperature. In addition, current measurements on two-sided metallised samples at electric fields of 3*10 6 to 5*10 7 V m -1 were carried out. The isothermal surface potential decay rates as well as the current-voltage characteristics show ohmic behaviour at low fields indicating intrinsic carriers. For fields higher than approximately=4*10 7 V m -1 the injection dominates. From the surface potential decay curves a trap modulated effective mobility mu of approximately=7*10 -15 m 2 V -1 s -1 at T=70 degrees C and a field strength E 0 =8*10 7 V m -1 was estimated, which is independent of polarity. A broad open-circuit TSC peak at approximately 80 degrees C is related to the conductivity. An anomalous current peak at about 40 degrees C appears only after being charged for a long time at room temperature (RT) or after freezing in the high-temperature polarisation; it is associated with dipoles. All the electrical properties are almost unaffected by sample stretching.