Analysis of interval III kinetic data for emulsion polymerizations

Abstract

A procedure is presented for the quantitative analysis of kinetic data obtained for Interval III of emulsion polymerizations. The commencement of polymerization directly in Interval III allows the rate coefficients for the entry of free radicals into, and the exit (desorption) of free radicals from, the latex particles to be determined from the early stages of the polymerization, when n⩽½(when termination is essentially instantaneous). The results obtained for styrene are in agreement with those derived from direct entry into Interval II and from relaxation studies; those from Interval III are less prone to uncertaintly arising from particle size changes. For n > ½, the dependence of the termination rate coefficient on the ratio of monomer to polymer in the latex particles is also obtained. The methods used to determine all rate coefficients obviate any assumptions as to the efficiency of capture of aqueous free radicals or the values of the rate coefficient for propagation or of monomer concentration within the particles.