부산대학교 도서관

This article deals with the failure of polyethylene pipes transporting chlorine dioxide (DOC) disinfected water under pressures of few bars. Accelerated aging tries made at 20 or 40°C show that the antioxidant is rapidly consumed in a superficial layer until a depth of about 1.2 mm. Carbonyl groups appear in a sharper layer of few hundreds micrometers. Natural aging results at various places, for various times up to about 30 years, reveal also a superficial attack with a depth of the order of 1.2 mm. An antioxidant loss by migration, in the whole sample thickness, is also observable. The shape of antioxidant concentration profiles indicates that the crossing of interfaces controls partially the whole migration kinetics. Failures, with brittle cracking, were observed in natural aging, after exposure times of the order of 5-15 years, i.e., far before the expected lifetime (50 years). A kinetic model has been elaborated to predict the time to failure. It is based on a chemical unit, which models the radical processes induced by DOC, and a mechanical unit based on an empirical creep law and a failure criterion depending of the molar mass calculated by the chemical unit. POLYM. ENG. SCI., 49:1642-1652, 2009. [C] 2009 Society of Plastics Engineers
INTRODUCTION This article deals with the effect of chlorine dioxide (DOC) on aging of polyethylene (PE) pipes for the transport of drinking water under pressure. In the first part of [...]