Thermodynamics of the formation of poly-(3-methyl butene-1 sulphone) from 3-methyl butene-1 and sulphur dioxide

Abstract

Ceiling temperatures T_c for the copolymerization of 3-methyl butene-1 with sulphur dioxide have been measured for mixtures with mole fraction x_m of 3-methyl butene-1 from 0.025 to 0.951. These T_c values have been combined with the corresponding monomer activity coefficients (f_m and f_s) to test the equation T_c=ΔH_lc/(ΔS_lc+R ln x_mx_sf_mf_s),where ΔH_lc and ΔS_lc are the enthalpy and entropy changes for the conversion of 1 mole of each of the pure liquid monomers into 1 basemole of condensed 1 : 1 copolymer. A substantial discrepancy between polymerization in olefin-rich and sulphur dioxide-rich mixtures has been found as was previously observed for isobutene + sulphur dioxide mixtures. The discrepancy is unaffected by the method of initiation and is not due to any variation from 1 : 1 composition of the copolymer. The explanation is believed to be a difference in the free energy of the polymer produced in different media, resulting from a variation in conformation on precipitation.