Ageing of polyethylene at raised temperature in contact with chlorinated sanitary hot water. Part I - Chemical aspects |
| |
Authors: | J. Castillo Montes D. CadouxJ. Creus S. TouzainE. Gaudichet-Maurin O. Correc |
| |
Affiliation: | a Centre Scientifique et Technique du Bâtiment Nantes, 11 rue Henri Picherit, BP 82341, 44323 Nantes Cedex 03, France b Laboratoire d’Etude des Matériaux en Milieux Agressifs, EA3167 Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle Cedex 1, France c Veolia Environnement Recherche et Innovation, Chemin de la Digue, B. P. 76, 78603 Maisons-Laffitte Cedex, France |
| |
Abstract: | In France, hot water quality control inside buildings is occasionally assured by disinfection treatments using sodium hypochlorite (between 0.5 and 1 ppm residual free chlorine). This disinfectant is a strong oxidizer and it could interact with metallic and polymer pipes used in hot water systems. To assess the long-term performance of these pipes, it is then necessary to study the impact of these treatments on the material behaviour, in particular for polymeric materials, even at relatively low disinfectant concentrations as used in potable water treatments. The objective of this work was to study the influence of sodium hypochlorite concentration on PERT/Al/PERT (PolyEthylene Raised Temperature) pipe degradation. Pipe samples were filled with chlorinated water solutions (concentrations ranging between 0 and 100 ppm) and maintained in static conditions during 270 days at 70 °C. The antioxidant depletion profile through a PERT wall was monitored using the oxidation induction time (OIT) method, which is a conventional technique of Differential Scanning Calorimetry. Chemical changes on the aged polymer were checked by Infrared Spectrometry. OIT change showed that the PERT stabilizing system was rapidly chemically consumed by the action of chlorinated water at 25 and 100 ppm concentrations. However, PERT degradation was strictly confined to the immediate inner wall. Only a 0.3 mm thick layer (inner part of the pipe) showed significant antioxidant depletion. An increase of the OH and C-O-C infrared bands was also observed on inner part of any samples during ageing which characterize the oxidation of the PERT on the inner wall. |
| |
Keywords: | Polyethylene raised temperature pipe Degradation Sodium hypochlorite Chlorinated water |
本文献已被 ScienceDirect 等数据库收录! |
|