Preparation of vinyl chloride‐ethylene copolymers by partial reduction of poly(vinyl chloride)

Reductive dechlorination of poly(vinyl chloride) with tri‐n‐butyltin hydride was used to prepare a series of vinyl chloride‐ethylene copolymers covering the complete range of comonomer composition from poly(vinyl chloride) to polyethylene. Osmotic measurements of the molecular weight showed that polymeranalogous products were obtained by the reduction. IR spectra of the copolymers and UV‐VIS spectra of thermally degraded copolymers were utilized to verify the statistical distribution of comonomer units in the polymer. The copolymers containing more than 73 mol‐% ethylene units show appreciable melting during thermal analysis with differential scanning calorimetry. The relationship between the melting temperature and the composition of the copolymers with a high content of ethylene can be expressed by Flory's equation. The reciprocal glass transition temperatures of vinyl chloride‐ethylene copolymers with high contents of vinyl chloride units change linearly with the weight fraction of vinyl chloride in the copolymers. The influence of the composition and the glass transition temperature on the thermal dehydrochlorination is discussed.