Analysis of Rigid Polyurethane Foams by Near-Infrared Diffuse Reflectance Spectroscopy

Abstract

The method of near-infrared diffuse reflectance spectroscopy is used to determine the compression and thermal properties of rigid polyurethane foams. Principal components analysis (PCA) of the spectra of the foams indicates that NIR spectroscopy can be used to discriminate between foams that were prepared from different polymeric formulations. Partial Least-Squares (PLS) calibrations of NIR spectra to the compression modulus, compression strength, deformation at failure, and K-factor (thermal conductivity) were also done. Results indicate that NIR spectroscopy can determine the compression modulus within 63.6 psi, compression strength within 2.63 psi, deformation at failure within 1.29%, and K-factor within 0.0089 Btu-in./°F-h-ft².