Kinetics of radiation‐induced bulk polymerization of vinyl chloride in the temperature range of −50 to 90°c

Abstract

Kinetic investigations on the bulk polymerization of vinyl chloride initiated by exposure to ⁶⁰Co γ‐rays were carried out in the temperature range of −50 to 90°C at dose rates varying from 0.15 to 50 rad/c. Some polymerization runs were also carried out in a centrifugal field. As generally reported for this polymerization system, in which the polymer is insoluble in the monomer, the polymerization rate was found to change as a function of the amount of the polymer formed in a special fashion. This particular function has been shown to be greatly influenced by the polymerization temperature and to be independent of the rate of initiation, or, more rigorously, of the dose rate. Thus, at any given temperature the equation of the polymerization conversion rate could be written in the form of the product of two separate functions, one for the polymerization conversion and the other for the dose rate. While for the latter the results gave an essentially square‐root dependence on dose rate as is normally found for homogeneous polymerization, the former has been discussed in the terms of recently advanced kinetic schemes, based on a two‐phase polymerization model. The kinetic parameters found in this work are in agreement with previous authors' data.