Orientational Measurements in Polymers Using Vibrational Spectroscopy

The mechanical properties of polymers are strongly influenced not only by the structure of the material but by the magnitude of the molecular orientation. Thus a great deal of interest exists in information about the molecular orientation in samples introduced by drawing or other forming processes. Several techniques of evaluation of this orientation exist such as birefringence, x-ray diffraction, sonic modulus, and fluorescence measurements l, 2]. Vibrational analysis of oriented polymers provides a method of determining independently the molecular orientation both in the crystalline and amorphous phases of polymers. By using vibrational techniques, a number of macromolecules have been studied in the solid state for a variety of different processes. It is the purpose of this review to summarize the recent theoretical and experimental results which have occurred since the review of Zbinden 3]. Infrared and Raman measurements will be reported since they are complementary to each other in their applications and results.