Degradation of polyethylene pipes by water disinfectants
TypeChapitres d'ouvrages scientifiques
Polyethylene (PE) pipes are commonly used for the transport of drinking water under pressures of few bars. There is an abundant literature on the results of isobaric and isothermal ageing tests made in pure water. These results show that, at ambient temperature, in the pressure domain of practical interest, the pipes perish by brittle fracture with lifetimes exceeding 50 years. There were considerable research efforts, in the past half century, to optimize the polymer structure and processing conditions in order to improve the pipe durability. In the last decade, however, it was discovered that disinfectants, of which the effect was ignored in previous studies, attack the antioxidants and, presumably, shorten the pipe lifetime because PE can undergo an oxidative degradation. This deleterious effect is especially pronounced when chlorine dioxide is used as a disinfectant, but chlorine and bleach lead also to measurable effects. The present chapter is aimed to answer the following question: Is it possible to build a kinetic model leading to a prediction of the time to failure for a given PE pipe, at given couple of temperature and pressure, for a given disinfectant in a given concentration in water? Such an investigation must cover three very distinct domains which will constitute the three main sections of this chapter: 1. Chemical aspects: Mechanisms and kinetics of disinfectant-antioxidant and disinfectant-polymer reactions, role of oxygen, macromolecular processes (chain scission) having consequences on the mechanical behaviour; 2. Transport phenomena: Penetration of disinfectants or their by-products in PE, loss by extraction and evaporation of antioxidants, couplings between these processes, composition and structure gradients resulting from diffusion controlled reactions; 3. Mechanical aspects: Kinetic modelling of pipe fracture under pressure. Coupling with chemical degradation
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Stabilizer thickness profiles in polyethylene pipes transporting drinking water disinfected by bleach COLIN, Xavier; VERDU, Jacques; RABAUD, Benjamin (Society of Plastics Engineers, 2011)Polyethylene connection pipes of wall thickness ranging from 3.0 to 4.5 mm, used for 0, 5, 9, 12, and 18 years in the French network of drinking water disinfected by bleach, have been analyzed. The stabilizer thickness ...
Thermo-oxidation behaviour of composite materials at high temperatures: A review of research activities carried out within the COMEDI program LAFARIE, Marie Christine; GRANDIDIER, Jean Claude; OLIVIER, Loic; COLIN, Xavier; VERDU, Jacques; CINQUIN, Jacques (Elsevier, 2010)The present paper presents a review of the main activities carried out within the context of the COMEDI research program, a joint collaboration involving three research teams focusing on the thermo-oxidation behaviour of ...
RICHAUD, Emmanuel; AUDOUIN, Ludmila; COLIN, Xavier; FAYOLLE, BRUNO; VERDU, Jacques (In Tech, 2012)Polymers having an aromatic backbone polymers have a high mechanical strength and a high modulus. Their aromaticity increases their resistance for use in relatively severe conditions especially in aerospace and nuclear ...
AUDOUIN, Ludmila; COLIN, Xavier; FAYOLLE, Bruno; RICHAUD, Emmanuel; VERDU, Jacques (EDP Sciences, 2010)It has been supposed, for a long time, that kinetic modelling of polymer ageing for nonempirical lifetime prediction was out of reach for two main reasons: hypercomplexity of mechanisms and heterogeneity of reactions. The ...
COLIN, Xavier; MONCHY-LEROY, Carole; VERDU, Jacques (ELSEVIER, 2011)Three high density polyethylene (PE) samples of different origins, with weight average molar masses ranging from 38 to 63kgmol-1 and displaying a semi-ductile behavior with strain at break εR values of the order of 100-140%, ...