The thermal degradation of poly(methyl vinyl ketone) and its copolymers with acrylonitrile

It was confirmed that the thermal degradation of poly(methyl vinyl ketone) is a random reaction in which water is liberated from pairs of adjacent units resulting in conjugated sequences of limited length. When methyl vinyl ketone units are incorporated into polyacrylonitrile molecules by copolymerization the rate of thermal colouration is greater than in pure polyacrylonitrile, the rate of elimination of water is greater than from pure poly(methyl vinyl ketone) and the extensive colouration which occurs in polyacrylonitrile is maintained in the copolymer. These features of the thermal degradation of the copolymer are explained in terms of a series of reactions of a similar type to the propagation process of the chain reaction responsible for the colouration of polyacrylonitrile. In support of this it has been shown that by the use of appropriate initiators a chain reaction can be made to occur in poly(methyl vinyl ketone) which results in elimination of water and the production of extensive conjugated sequences.