Critical conversion in the processes of polymer formation

Abstract

Relations between the critical conversion of gelation αc and the conditions of polymer formation by living and terminated polymerization were studied. It was shown that the weight average functionality of the initial system given by the formula , φ22(0) = ∑i(i-1)mi where mi is the initial concentration of an i-functional monomer, is the parameter determining the value of αc. Formulas relating the critical conversion to the kinetic parameters of polymerization processes are presented. For polycondensation processes the kinetic equation based on the concept of bond blocks is proposed. It allows for estimating the gel point even for systems in which the substitution effect takes place for one of the components. The equation α∑(i-1)ni = 1 is , where α is the current conversion and ni are the values specifying the concentrations of i-functional blocks. The latter values are functions of α and may be calculated kinetically.