Defect induced infra-red absorption of polymers

Polymeriesystems never possess an ideal structure but contain a considerable amount of chemical and structural imperfections.The vibrational properties of polymer systems considered as defect containing crystals are discussed.The features of the infra-red and Raman spectrum are qualitatively predicted.The major advancement of the vibrational spectroscopy of these systems is the present possibility of •calculation of the density of vibrational states both for ideal and defect containing molecules.The use of the density of states for the interpretation of the vibrational spectra of these systems is discussed and its limitations are pointed out.The vibrational spectrum of solid polyethylene is analysed and conclusions on the existence of various types of conformational defects are derived.A possible interpretation of the spectrum of polyethylene single crystals is suggested.