The study of the orientation of polyvinyl chloride films by means of birefringence and infrared, visible, and ultraviolet dichroism

The ultraviolet, visible and infrared dichroism and birefringence of a series of stretched polyvinyl chloride (PVC) samples containing polyene structures prepared by chemical dehydrohalogenation is studied. A theory is developed relating the dichroism and birefringence of a segment of a polymer molecule to the length (and stiffness) of that segment. Values of the principal absorbances and polarizabilities of the polyene segments which are required for the theory are calculated. The theory is applied to interrclate these optical measurements in a satisfactory manner and to provide a means of experimentally determining the orientation of PVC in an oriented film.