EFFECT OF ETCHING TREATMENT ON THERMALLY STIMULATED CURRENT IN SPHERULITIC POLYPROPYLENE

Charging saturation and thermally stimulated currents (TSCs) were studied for positively corona-charged spherulitic and nonspherulitic polypropylene films which were etched with a mixture of H2SO4 and K2Cr2O7. From the experimental results of the etching treatment effect on the TSC spectra, it is concluded that the charging saturation is caused by a decrease in the number of traps located in the amorphous part of the polymer. For spherulitic polypropylene, estimated values of trap density which is effective at room temperature were 2.5-1.1 x 10(14) [cm-3], depending on the extent of etching treatment. The densities of traps located in the crystalline parts of the nonspherulitic and spherulitic polypropylene were 0.93 x 10(14) [cm-3] and 0.76 x 10(14) [cm-3], respectively.