GB1042149A - Polymerization of episulphides - Google Patents

Abstract

Polyepisulphides are prepared by polymerizing at least one episulphide which is free from aliphatic unsaturation in the presence of a catalyst comprising a carbonate of a metal of Group IIB of the Periodic Table. Preferably the catalyst is activated prior to use by heating to an elevated temperature which is below the decomposition temperature of the carbonate. The preferred catalyst is zinc carbonate which may be heated before use, preferably to 140-350 DEG C., particularly 200-300 DEG C. Suitable monomers include ethylene, propylene, butylene, phenylene and styrene sulphides. Polymerization may be effected by the emulsion or solution polymerization techniques, preferably the latter. The products obtained from propylene sulphide using cadmium carbonate as the catalyst are said to be partially crystalline, whereas those obtained with zinc carbonate are amorphous. Example I describes a series of experiments in which propylene sulphide is polymerized in the presence of treated and untreated zinc carbonate and, in some cases, in the presence of diethyl ether. In Example 2 propylene sulphide is polymerized in the presence of zinc carbonate which has been heated to various temperatures. Example 3 demonstrates the use of a variety of inert solvents for the propylene sulphide/zinc carbonate system. In Example 4 cadmium carbonate is used as a catalyst for propylene sulphide polymerization.