Kazuyoshi Ogino

Comparison of Osmotic Pressures for the Poly (γ-benzyl-L-glutamate) Solutions with the Theories for a System of Hard Spherocylinders

Abstract Osmotic pressures for the poly(γ-benzyl-L-glutamate)-dimethtylformamide system were obtained over the concentration range covering the isotropic and anisotropic phase. Three smplesn were examined at three temperatures. The system was athermal for the isotropic phase. The equation of state (the concentration dependence of osmotic pressures) was compared with the existing therories of liquid of risgid spherocylinders. The equation of state for the isotropic phase was reasonably satisfeied 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 phases was not so large as predicted from its theory. The phase transition concentrations were observerd 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.

Thermodynamic properties of concentrated poly(γ-benzyl-l-glutamate) solutions

Abstract Solvent activities for the poly(γ-benzyl- l -glutamate)-chloroform system were obtained in the concentration range of 20 to 100 vol % polymer at 30°C by isothermal distillation and vapour pressure measurements. The results were combined with osmotic pressure data reported previously and were compared with the existing theories for solutions of rodlike molecules. Coexistence of two phases was not found. The data could be explained by the Flory theory, as modified by Wee and Miller, in a low or intermediate concentration range, and could be explained by the Flory-Leonard model at high concentrations.

The pressure effect on the thermodynamic properties of polystyrene—trans-decalin solution

Abstract The viscosity of a solution of polystyrene in trans-decalin was measured over pressure and temperature ranges from atmospheric pressure to 400 kg/cm2 and 20° to 40°C. The viscosity measurements at elevated pressure were made by the use of a rolling-ball type viscometer, and the validity of this method was confirmed by comparing with the calibrated Ubbelohde viscometer at atmospheric pressure. Values of the interaction parameter, χ, were obtained from the coil expansion coefficients on the assumption of the fifth-power rule of the Flory theory for the expansion of the polymer molecules in the solution. χ1 increases with increasing pressure. The pressure coefficient of the theta-temperature calculated from the pressure and the temperature derivatives of χ1 is in good agreement with the result of Schulz et al. The values of χ1 were compared with those calculated from the new Flory theory and the Patterson theory for polymer solutions. At lower pressure these theories predict the behaviour of χ1 well, but at higher pressure the prediction becomes inaccurate.

On the Vibrational Properties of High-Elastic Gels

A new method is presented for determining dynamic mechanical properties of high-elastic gels by measuring the amplitude and phase of forced longitudinal vibrations excited in get blocks themselves. It is shown that the Youngs modulus and viscosity can be determined by analysing these quantities. Theoretical analyses are also made for the vibrations excited in the vertical cylindrical samples with no viscosity by horizontal oscillations of the bottom ends. The calculated results are illustrated by strains (displacement, inclination and shearing angle) for various values of cylinder diameters and frequencies used. It is shown that an approximate value of rigidity can be obtained from the frequency dependence of the strains. On an basis of this method the dependence of dynamic mechanical constants of agar-agar gels on cylinder diameters, concentrations and frequencies is studied, and reasonable values are obtained.