Polyurethane coatings are widely used due to their excellent flexibility, abrasion resistance, Ultraviolet stability, and chemical durability. However, quantitative evaluation of their aging behavior remains a challenge. In this study, two aliphatic acrylic polyurethane topcoats were subjected to accelerated cyclic aging tests, and their degradation processes were characterized by infrared spectroscopy and glossiness measurements. The ratio values of C═O/C–H band area with time for two aliphatic acrylic polyurethane topcoats were found to reflect the increasing of carbonyl content, which governs the transformation of surface microstructure and glossiness. A significant negative correlation between glossiness and the semiquantitative analysis of carbonyl groups was confirmed by Spearman correlation coefficients of −0.772 and −0.782, respectively. Furthermore, the relationship between glossiness and aging time was described by an exponential function, indicating that glossiness decreases progressively with extended exposure. These results provide a quantitative framework for assessing the aging performance of polyurethane coatings and offer a basis for predicting their long-term durability under ultraviolet exposure.
Xiang et al. (Sat,) studied this question.