Influence of nonylphenol-polyglycol-ether environments on the results of the full notch creep test

It is well known that resistance to slow crack growth (SCG) is important for the lifetime of pressurized polyethylene (PE) pipes. To investigate the SCG resistance, the full notch creep test (FNCT) is widely used, especially in Europe. It is generally accepted that FNCT times to failure correlate with results from internal pressure tests on pipes. Nevertheless, the reliability of the FNCT is regularly discussed in the relevant literature. In this research work the degradation of the surface active environment (2% wt Arkopal N110 in deionized water) was verified and it was found that the times to failure increase continuously with the age of the solutions. Furthermore, it was interesting that PE films stored in Arkopal solutions had a lower OIT value compared to samples stored in water. After these preliminary tests, a ranking of several PE pipe materials was established.