Multiple (partial-), main glasstransitions and tacticity of polyurethanes, polymethacrylates and styrene-copolymers measured by thermal diffusivity

Abstract

Test polyurethanes have been prepared by adding two kinds of urethane — prepolymers of known content of segments with very different partial transitions. Their thermal diffusivity curves verify an assumption that the amount of thermal diffusivity change is proportional to its percentage of segments. Basing on these results a series of copolymers ofN-butylmethacrylate with styrene was investigated. These copolymers have three transitions which are interpreted. Some polymerization methods were investigated by polymerizing ethylmethacrylates in solutions of toluene and dimethoxyethane. Thermal diffusivity curves show three partial transitions caused by different tactic sequences. The influence of solvents on the tactic polymerization of ethylmethacrylates with butyllithium is investigated, formamide gives highest amounts of tactic sequences. The tactic influence of methyl-, ethyl-, propyl-, isobutyl- andN-butylestergroups of methacrylates on polymerization in bulk with benzoylperoxide is investigated.