Abstract
Thermoluminescence glow curves displayed by ethylene-vinyl acetate copolymers after u.v. irradiation at low temperature have been compared to the depolarization thermocurrents (DTC) described in a previous publication, in order to establish a possible correlation between the thermal liberation of the trapped carriers and the intrinsic relaxation phenomena. The detailed analysis of these glow curves has been carried out, either by studying their spectral distributions between 300 and 650 nm, or by the systematic application of the classical method of partial glow and by a method of partial irradiation which consists in irradiating the sample isothermally at different temperatures in several experiments. Two main glow peaks corresponding to distinct spectral emission zones were found. These peaks occur in temperature zones similar to those of appearance of the DTC peaks; the latter were assigned to primary and secondary dipolar relaxations, i.e. α and β type relaxations, respectively. In addition, the β glow peak presents properties comparable with those of the DTC β peak and hence results probably from thermal untrapping, this untrapping being at least partly assisted by short range chain motions in the polymer. The α glow peak, on the other hand, shows little correspondence with the DTC peak and has essentially a superficial origin; it probably arises from two distinct traps associated with impurities or with interface between amorphous and crystalline regions rather than from the polymeric chains themselves.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.