Characterisation of accelerated ageing devices for prediction of the service life of acrylic-melamine/urethane thermosets

Acrylic-melamine/urethane thermosets are widely used as topcoat materials in the automotive industry. End users and manufacturers require an accurate prediction of the service life of these materials. Despite the significant interest in the topic of service life prediction, no overview of the subject has been presented. This article characterises the influence of light, oxygen and water on these thermosets in an effort to improve the procedures used to evaluate the degradation. Degradation was tracked using two spectroscopic and one mechanical degradation criteria. Based on the evolution of these criteria under artificial and natural ageing, four accelerated ageing devices (SEPAP 12/24, SEPAP 'water spray', WOM and QUV-B) were used. The results were used to calculate the acceleration factor between natural and artificial weathering to allow for a true service life prediction of these thermosets.