INSITU STUDY OF PHOTOPOLYMERIZATION BY FOURIER-TRANSFORM INFRARED-SPECTROSCOPY

The Fourier transform infrared (FTIR) in situ method was developed for the investigation of photopolymerization. Ultraviolet (UV) cure of a mixture of a cycloaliphatic epoxide, a 2-ethylhexyl acrylate, and photoinitiators, which forms simulataneous interpenetrating polymer network (IPN), was monitored while the sample was irradiated with UV light. Triphenylsulfonium salt and benzoin ether were used as photoinitiators. For the sake of comparison, similar experiments were performed for the epoxide with the triphenylsulfonium salt photoinitiator and the acrylate with the benzoin ether photoinitiator. The epoxy photopolymerization was monitored using an epoxy CH stretching band at 3005 cm-1 and a ring vibration band at 790 cm-1. The acrylic photopolymerization was monitored using a C = C stretching band at 1637 cm-1. The epoxy conversion was less than 60% when the acrylic polymerization was completed in the IPN.