Near Infrared Pleochroism. II. The 0.8–2.5μ Region of Some Linear Polymers

Abstract

Polarized radiation is used to study the pleochroism of aligned specimens of polythene, Nylon, polyvinyl alcohol, polyvinyl chloride, and polyvinylidene chloride, in the 0.8–2.5μ overtone and combination region. Assignments of observed absorption bands to various vibration modes of (coupled) >CH2, N–H, and C=O groups are attempted. The symmetry of an infinite planar-zigzag >CH2 chain is discussed as an approximation to that of polythene and, to a lesser extent, Nylon. Some limitations in the interpretation of observed pleochroism and in the application of selection rules are discussed. A pleochroism study, with unpolarized radiation, is made of the molecular alignment in oriented ``Parowax.'' A study is made also of the rupture of the intermolecular N–H≡O bonds in molten and premolten Nylon.