DRAWING AND ANNEALING EFFECTS ON THERMALLY STIMULATED CURRENTS IN POLYPROPYLENE FILMS

Thermally stimulated currents (TSCs) were examined in a temperature range from room temperature to 170-degrees-C for positively corona-charged polypropylene films which were, before charging, uniaxially cold drawn to different drawing ratios D up to 3.5 or were annealed at different annealing temperatures T(a) after drawn to D=3. Two main TSC bands P+1 and P+2 were observed around 60 and 140-degrees-C, respectively. The peak temperature of P+1 strongly depended on D and T(a): It shifted toward higher temperature by drawing while it turned to shift toward lower temperature by annealing.