Mechanical, thermal and physico-chemical behavior of virgin and hydrothermally aged polymeric pipes

Abstract

In this paper, an experimental study was conducted to characterize industrial PVC pipes and to investigate the effect of hydrothermal aging on their physico-chemical, thermal, and mechanical behavior. Three temperature (25°C, 60°C and 90°C) and full immersion in distilled water were retained as accelerated hydrothermal conditions. Kinetic of water absorption was examined and Fickian behavior was observed. The aging temperature was found to influence the water uptake behavior of PVC samples. Thermogravimetric analysis (TGA) has proved that the pipe material is not pure, while it consists of PVC reinforced with calcium carbonate (CaCO3). After exposure to accelerated aging, TGA and FTIR analysis exhibit preliminary signs of degradation of PVC samples under the retained conditions. Changes affecting the shape and the color of aged samples were examined. Mechanical properties have been characterized, after immersion of 30 days, with an improvement of strength and stiffness of the aged samples, in particular at elevated aging temperature. However, the aging response is accompanied by a loss of ductility for the aged material. These results, even for brief exposure, could help to understand the behavior of PVC composite pipes under hydrothermal conditions.