Transient Current of Polyimide in the Time Range 10-4-101 Sec at Temperatures 180-280°C

The transient electric current is obtained by applying a step voltage of 167 V on Kapton(R) type H-films of 25 and 76 pm thickness. The current consists of two components: one decays fast originating from a dielectric relaxation having approximately a single relaxation time ¿; and the other is almost flat due to electric conduction. We find a correlation between the conductivity ¿ and the relaxation parameters which is close to ¿=¿0¿¿¿/¿, where ¿¿ is the permittivity of free space and ¿¿¿ is the change in relative permittivity, suggesting that the present dielectric relaxation is closely associated with the conduction process. The change in ¿ with heat treatment time is also discussed.