ANALYSIS OF REACTION-INJECTION-MOLDED POLYURETHANES BY NEAR-INFRARED DIFFUSE REFLECTANCE SPECTROSCOPY

The ability of near-infrared (NIR) diffuse reflectance spectroscopy to characterize reaction-injection-molded (RIM) polyurethane elastomers is demonstrated. The advantage of NIR spectroscopy over other analytical methods is its ability to analyze samples without any preparation. In this work, the specific effects of composition, density, phase separation, and moisture content on the NIR spectra of the polymers are identified. In addition, the ability of NIR spectroscopy to make rapid assessments of physical properties, such as heat sag and flex modulus, is demonstrated. In order to perform these analyses, the multivariate statistical methods of principal components analysis (PCA) and partial least squares (PLS) are used.