Near-infrared spectroscopy for in situ cure monitoring of dimethacrylate-based networks

In this study, near-infrared transmission spectroscopy is investigated as a n alternative technique for the real-time cure monitoring of thermosets sys tems, Two polymer systems based on dimethacrylate/styrene and dimethacrylat e/divinylbenzene monomers were studied in order to check the influence of c omonomer functionality. A new device utilizing ITO (indium-tin-oxide)-coate d glass plates was developed to take into account the specificity of chain polymerization: oxygen inhibition, bulk polymerization, etc. Two absorption bands at 6166 and 6135 cm(-1) suitable for in situ monitoring of methacryl ate and vinyl double bonds were identified, and the molar absorption coeffi cient was determined. A quantitative analysis allows us to calculate the do uble-bond conversion during the polymerization in isothermal conditions bet ween 60 and 80 degrees C.