Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

The radical polymerization of methyl methacrylate may be efficiently initiated by tert-butyl-hydroperoxide at 40°C and lower, deep below the temperatures of spontaneous hydroperoxide decomposition, when sulphuric acid simultaneously with ketones is used as the activator of peroxide decomposition. The initial reaction rate depends on concentration of initiator components, the exponents with regard to tert-butyl hydroperoxide, sulphuric acid and acetone being 0.25, 0.5 and 0.5, respectively. Water retards the hydroperoxide decomposition very efficiently and the polymerization rate is inversely proportional to the square root of water concentration in the system. Within the concentration range of hydroperoxide (1. 10^-3 - 3. 10^-2 mol dm^-3), sulphuric acid 2.62 . 10^-2 mol dm^-3 and acetone 0.2 mol dm^-3 the observed initial polymerization rate varies from 14.4%/hour to 34.5%/hour at 40°C. The concentration of water, introduced into the system by the polymerization components, was 0.05% in all cases. The activating effect of ketones upon the acid catalyzed hydroperoxide decomposition is accounted for by the formation of ketone-H₂SO₄ adduct that facilities the decomposition of hydroperoxide.