RHEOLOGICAL PROPERTIES OF CONCENTRATED SOLUTIONS OF STYRENE-ISOPRENE BLOCK COPOLYMERS.

Rheological properties of concentrated solutions of AB type copolymers in various solvents have been measured. The relationship between the rheological behavior and the structure formed in the solution and breakdown and re-formation of structure by shear were discussed in terms of the solvent power and the composition of the copolymers. viscosity at a constant rate of shear plotted against composition for solutions in DOP and KC4 shows a minimum at an intermediate St content. On the other hand, viscosity and sigma //R plotted against composition for solutions in DBP show a maximum at an intermediate St content. These facts suggest that one of the blocks forms aggregates and with the other block being cilia, and that the number of molecules aggregated decreases with decreasing block length.