Simultaneous thermally stimulated luminescence and conductivity in low-density polyethylene
Year: 1988
Type: article
Abstract: Thermally stimulated luminescence (TSL) and conductivity (TSC) in low-density polyethylene samples were measured simultaneously, while the sample was being heated to room temperature after X-ray irradiation at -190 degrees C. The TSC curves of samples from which absorbed air had been removed showed five peaks, labelled C 1 -C 5 in order of increasing temperature, while the TSL glow curves showed only three peaks (L 1 -L 3 ). The effects on these peaks of (i) immersing the samples in fuming nitric acid, (ii) annealing them in vacuum, and (iii) exposing them to an oxygen/ozone mixture, were investigated. It is concluded that the C 1 and L 1 peaks are associated with the same traps, these traps being formed by the polymer chain themselves in the chain-fold regions of the sample, and being broken up by the onset of side-chain motion. The same is true for the C 2 and L 2 peaks, except that a different set of traps and 'crankshaft' motion are involved. There is no obvious correlation between the L 3 peak and any of the TSC peaks; the L 3 traps are also formed in the chain-fold regions, and are broken up by the glass transition. The C 3 , C 4 and C 5 traps are probably structural defects of various kinds in the crystalline regions of the samples, from which electrons escape by thermal excitation. When the samples contain absorbed air, a hitherto unreported peak is observed in the TSC curve, corresponding to the TSL 'gas' peak.
Authors: A Markiewicz, R J Fleming
Institution: Monash University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2085922014