ORIENTATIONAL STUDIES OF POLYMERS USING POLARIZATION MODULATION INFRARED LINEAR DICHROISM - EXPERIMENTAL PROCEDURE AND QUANTITATIVE-ANALYSIS

Orientational analysis of polymers using infrared linear dichroism has been improved by introduction of polarization modulation of the incident electromagnetic field. After a description of the experimental procedure, a general quantitative analysis of the detected signal is developed in order to obtain the dichroic difference of the sample. Polarization modulation experiments carried out on poly(vinyl chloride) and poly(methyl methacrylate) stretched films demonstrate the high sensitivity of this method, especially for very small elongations of these polymers. Indeed, the well defined behaviour of the orientation function <P2(COStheta)> provides evidences for very subtle rearrangements of the macromolecular chains.