Analysis of the reflectance of polymers in the near- and mid-infrared regions

Abstract

A non-destructive technique for evaluating polymers was achieved through reflectance measurements in the near-infrared (NIR) and mid-infrared (MIR) wavelength ranges. It is shown that the chemical nature of the materials, the grain sizes and the orientation of the fibers influence the shape of the spectra and the spectral reflectance values. Integrated reflectance values R, from 0.25 to 2.5 μm, for the solar radiation spectrum, are given for some commonly used natural and synthetic polymers. We show how the NIR and MIR spectroscopic features reflect the chemical nature and the physical state of polymers. They represent a powerful tool for the identification of samples presenting a broad range of morphologies such as bulk, powders or fibers. Principal component analysis (PCA) was employed to illustrate the effect of these parameters on the spectra.