EFFECT OF MAGNETIC FIELD ON RHEOLOGICAL PROPERTIES OF CELLULOSE ETHERS SOLUTIONS

Abstract

The rheological properties, structure and phase transitions of hydroxypropyl cellulose in ethanol, dimethyl sulfoxide, ethylene glycol solutions and ethylcellulose in dimethylformamide solutions are studied using viscometry, the cloud-point method, polarization microscopy, the optical interferometry and a polarization photoelectric apparatus in the temperature range 280-360 K. The temperature-concentration regions of isotropic and anisotropic phases are determined for all systems. The type of boundary curves of phase diagrams is compared with the chemical structure of macromolecules. It is shown that the constant magnetic field (3.6 kOe) leads to the orientation of macromolecules in solutions. The domain structure arising in solutions is fixed after evaporation of a solvent and shown in orientation of strips of the film relief. It was found that the flow curves of all solutions at 298 K in the range of shear rates from 0 to 15 s-1 are typically for the non-Newtonian liquids. It was found that the magnetic field leads to an increase in the viscosity of isotropic solutions and a decrease in the viscosity of anisotropic solutions. Both effects depend on the direction of the magnetic field lines. When the rotor-rotation axis is parallel to the direction of power lines of the magnetic field the change in the viscosity of solutions is greater than that at perpendicular orientation of the rotor-rotation axis and power lines of the magnetic field. The results are discussed using representations about the changes in the macromolecule conformation and in the size and shape of the supramolecular particles in the solutions during flow under a magnetic field with different orientation of the power lines.