Correlation of physico-chemical, mechanical and electrical properties of ultraviolet-degraded poly(ethylene terephthalate)

Abstract

Poly(ethylene terephthalate) (PET) films have been exposed to ultraviolet radiation. Changes in physico-chemical, mechanical and electrical properties which occur in the films were examined. It was found that the specific viscosity, tensile strength, elongation at break, relative dielectric constant and dielectric strength decrease, while the dielectric loss factor, density, optical density of the ir spectrum band which refers to the trans form of the PET molecule, as well as the quantity of carboxylic end groups, increase. Least squares analysis and function straightening methods were used for the interpretation of the experimental data. Correlating relationships between measured parameters were established using the same methods. Special attention was paid to the changes in the electrical properties of poly(ethylene terephthalate), because no data are available so far. Mathematical correlations with chemical and mechanical properties were established.