Study of the visible light curing of vinyl ester resins using in situ Raman spectroscopy

In-situ Raman spectroscopy was used for providing the direct measurement of the C = C molar concentration of typical visible light curing vinyl ester resin. Using cyclohexyl ring stretching mode at 748 cm-1 as reference, the back scattering configuration relative Raman cross section for epoxy vinyl ester resin of vinyl ester resins C = C stretching mode at 1,630 cm-1 and aromatic ring stretching mode at 1,602 cm-1 were obtained. The molar concentration of C = C during the curing process was monitored under three different powers. It was found that with the laser power increasing, the molar concentration change rising with time steadily, and visible light curing rate gradually speeding up. The residue C = C molar concentration after long curing process was quantified. This value may be useful for future design of visible light curing resins.