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Abstract
Copolymers of vinyl acetate and ethylene were prepared by emulsion polymerization using ammonium persulphate and sodium metabisulphite as initiators in presence of cyclohexane. Several copolymer samples were prepared by changing initial pressure of ethylene from 100 to 250 psi. The copolymer composition was determined by 1H-NMR and thermogravimetric analysis in nitrogen atmosphere.
Using thermal volatilization analysis with differential condensation of volatile products, with film samples on flat-bottomed silica glass reaction tubes to permit measurements of UV spectra of partly degraded polymer, the thermal stability, the types of volatile products and the development of conjugation in the involatile residue have been compared for poly(vinyl chloride), polychloroprene, poly(vinyl acetate) and vinyl acetate/ethylene copolymers, poly(vinyl formate) and poly(vinyl alcohol). All undergo a side-group elimination reaction at lower temperatures, and polyene breakdown occurs in all the samples between 400 and 500°. The longest polyene sequences are formed by PVC. All the polymers except PVC show some complexity of products in the elimination reaction.
