Emulsion polymerization of styrene. I. A reproducible system

Abstract

Excellent reproducibility of an emulsion polymerization of styrene has been obtained in a nitrogen atmosphere and a technique and apparatus have been described to obtain this reproducibility. The rate of polymerization for this system has been shown to be proportional to the square root of the catalyst concentration and to increase with higher catalyst concentrations. Average molecular weights were higher with higher concentration of catalyst within the catalyst concentrations studied and polymerization occurred without significant pH changes. In contrast, reproducibility of the emulsion polymerization in air atmosphere was unsatisfactory. The presence of air (oxygen) increased the induction period, decreased the rate of polymerization and decreased the average molecular weight of the polymer. Since the time necessary for polymerization was increased, the decrease in pH was considerable during the polymerization.