COMPARISON OF OSMOTIC PRESSURES FOR THE POLY(GAMMA-BENZYL-L-GLUTAMATE) SOLUTIONS WITH THE THEORIES FOR A SYSTEM OF HARD SPHEROCYLINDERS

Osmotic pressures for the poly( gamma -benzyl-L-glutamate)-dimethylformamide system were obtained over the concentration range covering the isotropic and anisotropic phases. Three samples were examined at theee temperatures. The system was athermal for the isotropic phase. The equation of state (the concentration dependence of osmotic pressures) was compared with the existing theories of liquid of rigid spherocylinders. The equation of state for the isotropic phase was reasonably satisfied by the modified Cotter theory if the decreased axial ratio was assumed for the polymer. The difference of the equation of state between the isotropic and anisotropic phase was not so large as predicted from its theory. The phase transition concentrations were observed using a polarizing microscope. The transition points were in rough agreement with its theory for shorter rods; for longer rods, they were much higher than predicted. It was deduced that the flexibility of the polymer softens the phase transition.