Kinetics of the dehydrochlorination of poly(vinylidine chloride). Part 1.—General nature of reaction and effects of temperature, molecular weight and morphology on the first stage of reaction

Abstract

A study has been made of the thermal decomposition of solid poly(vinylidene chloride). This paper is concerned with the first stage of reaction (the loss of one molecule of HCl from each monomer unit) and the influence on it of temperature, pelleting pressure, particle size and molecular weight. After an initial induction period the reaction (in the temperature range 150–190°C) exhibits first-order kinetics (rate constant k₁) towards a limit of 50% loss of HCl. The induction period has been characterized by an empirical equation involving the initial rate of reaction α₀k₁, and a parameter k₀ which determines the length of the induction period. The influence of the above factors on α₀, k₀, k₁ are reported. The data are discussed in relation to a proposed mechanism for the degradation reaction which takes specific account of the molecular structure of the solid polymer and stresses the importance of stereochemical factors.