EFFECT OF CHLORINATED WATER ON THE FATIGUE CRACK GROWTH RESISTANCE OF POLYETHYLENE COMPOUNDS WITH RECYCLATE CONTENT FOR PIPE APPLICATIONS
Paul J. Freudenthaler, Joerg Fischer, Mathias Eder, Reinhold W. Lang
# 2021 Amsterdam
For controlled water disinfection, typically chlorine is used and preliminary studies demonstrate its aging and crack growth acceleration effects on polyolefin pipe materials [1, 2]. Although the use of recycled plastics is not prohibited in some ISO standards for polyolefin piping systems [3–5], only small amounts are currently used in the European market. This is most likely a result of lacking experience and confidence in recyclates. The purpose of this paper is to gain an insight in the suitability of commercially available post-consumer recyclates, to be used in compounds, for piping applications. Therefore, fatigue properties of polyethylene (PE) pipe grade material with an enhanced resistance to crack growth (PE100-RC), of an injection-molding pipe grade PE80-IM, of a PE-HD post-consumer waste recyclate and of various compounds of PE100-RC and the PE-HD recyclate were tested in water and chlorinated water with a chlorine content of 5 mg/L. To investigate the temperature influence on the local aging effect of chlorine,superimposed fatigue crack growth (FCG) tests [6] were performed at room temperature and at 60 °C. The recyclate showed a higher dependence on temperature and chlorine content than PE100-RC. When comparing fatigue crack growth resistances, a distinct ranking between the PE compounds is possible. With higher amounts of recyclates in the compound, decreasing fatigue crack growth resistances were found. The 25 % recyclate compound performed better in terms of FCG than the tested PE80-IM grade.
