The thermo-oxidative degradation of PBT molded parts has already been evaluated in relation to mileage. However, in this study we attempted to evaluate thermo-oxidative degradation in relation to the product of thermal aging temperature and ageing time by applying time-temperature superposition principle law. The following contents became apparent as a result.
·Degradation could be evaluated by considering factors related to temperature, such as the car model and installation environment of parts.
·Service life could be estimated from the relation between the thermo-oxidation degradation and mechanical properties, while improving the precision of degradation evaluation.
·The applicable temperature range, originally between 80°C and 120°C, was extended up to 180°C.
·We also tried to apply this law to materials other than PBT such as PP and PA 66. As a result, it was found that PP and PA 66 were available in the temperature ranges between 80°C and 120°C and between 120°C and 150°C respectively.
·It was therefore suggested that this law could be further developed as a general-purpose method to evaluate degradation of polymers.
