Oxidative lifetime prediction of a polypropylene woven geotextile by applying high temperature and moderately increased oxygen pressure

Abstract

Resistance to oxidation of a polypropylene (PP) woven geotextile was determined by performing and evaluating various high-pressure autoclave tests (HPAT). Unlike that proposed in the corresponding ISO standard and the majority of HPAT studies published, tests were performed at slightly elevated oxygen pressures (pO2) of up to 500 kPa. Extrapolations were carried out with regard to temperature and oxygen (partial) pressure. The times-till-failure results obtained indicate an Arrhenius dependency with respect to temperature (T) and a reciprocal dependency with respect to oxygen pressure. The relationship found between time-till-failure/service life and the two acceleration factors (T and pO2) is not an empirical one but is based on chemical reactions according to the basic autoxidation scheme. Since the oxygen pressure was monitored in the autoclave during the tests it was possible to directly determine the oxygen consumption rate and not just indirectly as is common practice via the determination of mechanical/physical properties. Furthermore an accelerated oven test was performed and time-till-failure results from both methods were compared.