Structure and Morphology of Ethylene/Vinyl Chloride Copolymers

A series of ethylene/vinyl chloride copolymers with a random sequence distribution and a wide range of comonomer composition has been examined in the solid state by diffraction and microscopic techniques and 13C NMR. The copolymers had been prepared by reductive dechlorination of poly(vinyl chloride) with tributyl tin hydride. The degree of chlorine incorporated within the crystals was established for each copolymer by comparison of quantitative 13C NMR spectra (under high-power proton decoupling and magic-angle spinning) at temperatures above and below the melting point. X-ray diffraction showed that increasing the chlorine content results in expansion of the basal plane of the unit cell and in increasing intermolecular disorder. The random incorporation of chlorine into the chains also effects the morphology. Electron microscopy showed the lamellar characteristics to depart from those of poltethylene, although the preferred growth direction and the molecular tilt within the crystals are preserved.