Infrared Spectra of Polymer Mixtures—Problems Caused by Dispersion Effects in Difference Spectra

Abstract

Calculations of infrared difference spectra of polymer blends and pure components have been made based on models with no intermolecular bonding interactions. The results demonstrate that residual peaks can arise from optical phenomena based solely on the effects of differences in the real part of the refractive indices of the pure components. Accordingly, chemical interpretations, such as intermolecular bonding interactions, of residual difference peaks must be made with caution in blends where the real refractive indices of the components differ by several percent or more in absorption-free energy regions.