Test MethodOxidation induction time studies on the thermal degradation behaviour of polyoxymethylene

The thermo-oxidative stability of two types of commercially available polyoxymethylene (POM) in various ageing conditions has been studied by applying the Oxidation Induction time (OIt) method, which is a special technique of conventional differential scanning calorimetry (DSC). The results reveal that the proposed method is appropriate to characterise the stabiliser consumption in POM during thermal ageing. It is found that the OIt event is predominately based on endothermic processes under the applied experimental conditions, which is in clear contrast to polyolefins. However, the ability to differentiate different processed and aged POM samples decreases significantly with increasing OIt test temperature. Corresponding Arrhenius plots of the OIt results for POM reveal that straight line extrapolation from high to low temperatures is not feasible due to the two segment nature of the OIt.