In this study, dynamic mechanical analysis was performed on UV adhesives during both the continuous UV irradiation phase and the post-irradiation dark reaction phase. The results showed that the dark reaction continued after UV irradiation ceased, reaching a cure degree of 0.7, though at a slower rate than during continuous irradiation. Relaxation behavior during the dark reaction phase was found to be independent of the curing method (continuous versus dark reaction) and dependent only on the cure degree. Tan δ and stress evolution followed similar patterns regardless of the irradiation conditions. FEM simulations successfully reproduced the experimental observations, demonstrating their potential for predicting relaxation behavior during dark reaction curing.
OTANI et al. (Wed,) studied this question.