Gravimetric, mechanical and chemical characterization of different materials used in sewers systems: Polyvinyl chloride (PVC), polypropylene (PP) and high density polyethylene (HDPE), aged in sulfuric acid at 60°C

he effect of aging on mechanical and structural behaviors of PVC, PP, and HDPE was investigated by acid solution at 60°C. The curves of gravimetric measurements for PVC and HDPE during testing time reveal that the water absorption follows the Fickian process, while the curve of water absorption for PP follows a non-Fickian behavior. While the degradation progresses, an increase in tensile strength, a great drop in elongation at break and a clear brittle failure mode for PVC, PP and HDPE specimens was observed. The increase in tensile properties is due to the increase in crystallinity and cross-linking density. The decrease of tensile properties is due to the scission of molecular chain. The changes in functional groups were monitored by using the Fourier transform infrared spectroscopy (FTIR). These results show that the principal functions of polymers are the aliphatic hydrocarbons. After aging, the change and appearance of new peaks signify an oxidation of hydrocarbon groups (CC, CH) due to the acid attack, effect of temperature and aging time. These results show that there is a good relationship between the diffusion of solvent as well as the increase of time exposure and temperature on the mechanical properties and function of polymers.