Accelerated thermooxidative ageing tests and their extrapolation to lower temperatures

A procedure for the extrapolation of accelerated thermo-oxidative ageing tests to lower temperatures is proposed. The procedure involves a deconvolution of the global process into high- and low-temperature components where the extrapolation to low temperatures is carried out using the low-temperature component. The method was tested on stabilized and unstabilized polyisoprene rubber and was found to produce realistic estimations of the length of the induction period of oxidation so giving a more accurate estimation of the service life. However, to obtain the low-temperature values of the adjustable kinetic parameters, very low heating rates are required (0.04 K min -1, 0.1 K min-1) making the measurement process time consuming. Using this method, more realistic estimates of the durability of a material are obtained. © 2005 Akadémiai Kiadó, Budapest