BEHAVIOR OF AMORPHOUS POLY(ETHYLENE-TEREPHTHALATE) ANNEALED AT T-LESS-THAN-TG BY THERMALLY STIMULATED CURRENTS

Citation
J. Belana et al., BEHAVIOR OF AMORPHOUS POLY(ETHYLENE-TEREPHTHALATE) ANNEALED AT T-LESS-THAN-TG BY THERMALLY STIMULATED CURRENTS, Journal of Materials Science, 28(14), 1993, pp. 3805-3808
Citations number
15
Categorie Soggetti
Material Science
ISSN journal
00222461
Volume
28
Issue
14
Year of publication
1993
Pages
3805 - 3808
Database
ISI
SICI code
0022-2461(1993)28:14<3805:BOAPAA>2.0.ZU;2-J
Abstract
Thermally stimulated current (TSC) discharges in open circuit of amorp hous poly(ethylene terephthalate) (PET) corona-charged electrets show a heteropolar relaxation at 87-degrees-C, rho1, between alpha and rho peaks. This relaxation tends to become homopolar when the sample is an nealed at temperatures below the glass transition temperature. This is due to the formation of a trapped charge density on the surface of th e material that originates, during the TSC discharge, a current that c ounteracts the one that results in rho1. This trapping effect, which i nitially is null, increases with annealing due to the rise in resistiv ity. On the other hand, TSC discharges in short-circuited annealed sam ples result in a heteropolar peak, rho, that corresponds to rho1. The area of rho increases with the annealing time in a bounded way. This peak is related to the formation of thermal nuclei (embryos) in the b ulk of the material that act as heterogeneities. This suggests that rh o1 is associated with a barrier-type polarization. If the annealed sam ple is heated to temperatures above the glass transition temperature, the tendency to the inversion of rho1 vanishes and rho disappears, wh ereas alpha and rho are modified. This suggests that rho relaxation is related to a Maxwell-Wagner-Sillars effect.