Abstract

As a measure of the degree of curing of epoxy resins, the glass transition temperature, Tg, and the residual heat of reaction, ΔHr, are often used. In this study, near infrared spectroscopy and multivariate calibration [partial least squares regression (PLSR)] have been used to monitor the two variables, using differential scanning calorimetry (DSC) as the reference method. The epoxy under study was a commercial system consisting of the resin, trimethylolpropanetriglycidylether, and the hardener, 3-aminomethyl-3,5,5,-trimethylcyclohexylamine. Using samples cured under different conditions, calibrations resulted in root mean square errors of cross-validation (RMSECV) of 18 Jg⁻¹ for ΔHr (range for ΔHr: 6.1–231.3 Jg⁻¹) and 7.2°C for Tg (range for Tg: 41.5–98.8°C). Also, a PLSR model for mixing ratio of hardener and resin was obtained, resulting in a RMSECV of 0.0040 (range for mixing ratio: 0.180–0.380).

© 2003 NIR Publications

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