Photopolymerization of UV Curable Coatings Monitored by Raman Spectroscopy

Photopolymerization process of UV curable coatings based on epoxy acrylate/tripropylene glycol diacrylate was monitored by Raman spectroscopy. The consumption of C=C double bond in coatings was observed under UV irradiation. Quantitative analysis of curing degree versus UV irradiation time was investigated by fitting Raman spectra. The results indicated that the initiation efficiency of cleavage type photoinitiators and Irgacure 184 are superior to that of hydrogen-abstraction type photoinitiator. High photoinitiator concentration is beneficial for achieving fast photopolymerization rate and high final conversion. However, when the concentration of photoinitiator exceeds a certain value, the polymerization rate and final conversion will not increase evidently because of initiation efficiency and free volume effect.