Ultraviolet curing kinetics of cycloaliphatic epoxide with real-time Fourier transform infrared spectroscopy

The photo-induced curing kinetics of cycloaliphatic epoxide coatings were investigated with real-time Fourier transform infrared spectroscopy with an optical fiber ultraviolet curing system. The consumption of epoxy group as a function of time was obtained by monitoring of the oxirane absorbance in the 789-746-cm(-1) region. The effect of the type of epoxide, hydroxyl equivalent weight, ratio of oxirane to hydroxyl groups (R), photoinitiator, and exposure time on the curing reaction was investigated. In general, the rate of curing was dependent on the hydroxyl equivalent weight, R, type of epoxide, and photoinitiator. For formulations without polyol, both initiator concentration and exposure time had minimal effects on the curing reaction. However, for formulations with polyol, the curing a reaction was dependent on the initiator concentration. (C) 2003 Wiley Periodicals, Inc.