Weathering degradation mechanisms of chlorinated PVC

This paper reports the effects of natural and accelerated artificial weathering on the physical, chemical and mechanical properties of Chlorinated PVC (CPVC) pipe material. Natural outdoor exposures were carried out for periods ranging from 2 weeks to 18 months. The accelerated artificial weathering was conducted by exposing samples to UV radiations for periods ranging from 100 to 3000 h. The tensile test results show that natural and accelerated weathering had limited effects on the strength and stiffness of the material. However, the fracture strain was noticeably reduced after natural weathering for periods as low as 15 days and artificial UV exposure of 100 h. Physical examination of specimens revealed that both types of weathering resulted in gradual discoloration of the specimens. ATR-FTIR spectroscopy and UV–vis analyses of exposed surfaces showed that the photoreaction responsible for degradation of CPVC is most likely dehydrochlorination.