The laser flash‐initiated polymerization as a tool of evaluating (individual) kinetic constants of free radical polymerization, 3. Information from degrees of polymerization

Equations are derived for the number average and the weight average degrees of polymerization for the polymer forming in a laser‐initiated photo‐polymerization under pseudostationary conditions when termination occurs by disproportionation or recombination and if chain transfer is negligible. Analysis of the degrees of polymerization at various pulse separations leads to information on the rate coefficient of propagation (k p ) and on the product k t ρ (k t = rate coefficient of bimolecular chain termination, ρ = concentration of primary radicals produced in each flash). As k p 2 /k t may be evaluated from the rate and the weight average degree of polymerization P̄ w of a single pseudostationary experiment, at least in principle, a complete resolution into individual constants may be achieved. It is demonstrated in an example that the data obtained in this way for the polymerization of styrene at 25°C are well consistent with those originating from other methods.