The properties of solutions of polymers in good and poor solvents and of articles prepared from these solutions

Abstract

It is shown that when polar and non-polar polymers dissolve in various solvents either the mean square end-to-end distance and the intrinsic viscosity of the polymer molecules alters (good solvents), or stable associations are formed (poor solvents). The viscosity of concentrated solutions of polymers in good solvents is higher the greater the mean square end-to-end distance of the macromolecules or the intrinsic viscosity. On passing to poor solvents the viscosity coefficient of solutions of polar polymer changes, as a result of redistribution of bonds between active groups of the polymer molecules. With non-polar polymers this does not occur. The lowering of the Tg of polar polymers by solvents is dependent on the quality of the solvent, but this has practically no effect on the change in Tg of non-polar polymers. The mechanical strength of unorientated fibres prepared from solutions of polar polymers of equal concentration in various solvents, under identical conditions of precipitation, is dependent on the structure formed during the phase transition, which in turn is dependent on the structure of the concentrated solution.