Surface characterization of photodegraded poly(ethylene terephthalate). The effect of ultraviolet absorbers

The surface characterization of photodegraded poly(ethylene terephthalate) was investigated. Films obtained by bi-axial extrusion were exposed in a laboratory weathering chamber for periods of up to similar to 1100 h of irradiation. Samples prepared with and without an ultraviolet (UV) absorber were tested by infrared, UV-visible and fluorescence spectroscopy. The results indicated that the unstabilized films are very susceptible to the degradation effects causing a large deterioration, especially in surface layers. The presence of an ultraviolet light absorber effectively reduced the formation of carboxyl end-groups at the surface as well as in the bulk of the films. In the case of samples with UV absorber the fluorescence data showed a barrier imposed by this additive in the formation of the monohydroxy-terephthalate. Scanning electron microcopy of fracture surfaces showed that film ductility is highly reduced after exposure. (C) 2004 Elsevier Ltd. All rights reserved.