Prediction of the thermal degradation–induced colour change of acrylonitrile butadiene styrene products as a function of temperature and titanium dioxide content

• A new method can predict the long-term colour change of polymers. • Models can be used to determine the optimum amount of colouring agent. • For ABS products, TiO 2 does not reduce the rate of colour change above 3 wt%. In this study, we examined the thermal degradation–induced colour change of acrylonitrile butadiene styrene (ABS)–based titanium dioxide (TiO 2 )–doped products as a function of TiO 2 content and temperature. Based on the time–temperature superposition (tTS) principle and the CIELAB colour space, we proposed a methodology for developing a robust model to estimate the long-term colour change of polymers doped with TiO 2 at elevated temperatures. We used 800 h of measurement data to develop the model and validated the colour change predictions of the model in 1600 h. The average colour difference between the measured and modelled results at the application temperature range (below 80 °C) was <1.5, smaller than the just noticeable difference ( JND ) in the CIELAB colour space. We found that above a certain TiO 2 content (approximately 3 wt%), the colour retention of the ABS/TiO 2 specimens can no longer be improved by increasing their TiO 2 content. To show the applicability of the model, we present two simple case studies predicting the colour and appearance of a polymer product under constant and variable heat loads. The proposed methodology provides an excellent tool for design, as it can be used to determine the optimum amount of TiO 2 . Moreover, it accelerates and simplifies the design process.