Chapter 9 - Optical Behavior of Polymer Blends

Abstract

This chapter focusses on the optical behavior of polymer blends. The study of the optical properties of polymer blends is of interest for two reasons. A blend, being composed of two or more components, will scatter light. This may result in blend being cloudy or turbid in appearance, a property that affects the marketability of a polymer, particularly for applications such as containers and films. Also, the scattering and other optical properties such as birefringence and dichroism convey information about the structure of the blend that is desirable for the understanding of its mechanical, electrical, thermal, and other physical properties. The chapter also discusses other optical properties of blends such as birefringence, infrared dichroism, and Raman polarization. The interpretation of birefringence is often ambiguous because of its being a composite property reflecting the combined orientation of both phases whereas infrared dichroism has the potential of selectively measuring the orientation of a particular phase. In principle, the Raman polarization technique can be used to selectively study the orientation of components of a blend in a similar manner to infrared dichroism. The Raman technique has an advantage over the infrared technique in that samples of small size and appreciable thickness may be employed rather than the thin films usually required for infrared dichroism studies. The study of birefringence and infrared dichroism provides information about the deformation mechanisms of the blends that are dependent upon their morphology.