Diffuse reflection spectroscopy study of granular materials and their mixtures in the mid-infrared spectral range

Diffuse reflection spectroscopy was used in the mid-infrared (MIR) waveleng th range (2.5-22 mu m) to characterize polymer particles and their behavior when mixed with inorganic materials such as calcium carbonate, glass spher es or silver-plated glass spheres. Different variables governing the reflec tion properties of these materials were examined. It was observed, on one h and, that MIR spectra are characteristic - they are related to the physical state and to the chemical composition of the samples - and, on the other h and, that the reflectances of mixtures are strongly affected by the optical characteristics of the added compound. Moreover, the reflectances of compa cted samples are also significantly modified by the amount and the duration of the applied pressure. (C) 1999 Elsevier Science B.V. All rights reserve d.