FLOW BIREFRINGENCE OF HYDROXYPROPYL CELLU LOSE MOLECULES IN AQUEOUS AND ORGANIC-SOLVENTS

The flow birefringence of several fractions of hydroxypropyl cellulose (HPC) in water, ethanol, and tetrachloroethane was measured. The opti cal shear coefficients [n]/[eta] of HPC in water and ethanol are large and significantly exceed the value in tetrachloroethane. According to the theory, this effect is partly caused by the optical form effect t aking place in the two former HPC solutions. The comparison of experim ent and theory shows that the phenomenon observed represents the micro form effect. The data for the [n]/[eta] values in water and ethanol su ggest that water as a solvent may affect the configuration of the mono meric unit of HPC so as to increase its optical anisotropy.