The Effect of Microbarite Additive on Rheological Properties of Semidilute Aqueous-Saline Solutions of Polyanionic Cellulose

The influence of microbarite additive on the rheological properties of semidilute aqueous-saline solutions of two samples of carboxymethyl cellulose with high degree of substitution (polyanionic cellulose) and strongly different molecular mass (76 x 10(3) and 665 x 10(3)) has been investigated by means of rotational viscometry and rotational rheometry. It has been shown that the introduction of microbarite in the solutions of high-molecular polyanionic cellulose leads to flocculation followed by precipitation, which is accompanied by the decrease in the systems viscosity. In the case of solutions of low-molecular polyanionic cellulose, the introduction of the additive has favored the formation of visually uniform systems stable during prolonged keeping and the increase in viscosity. In both cases, the introduction of microbarite in the solution altered its viscoelastic properties. The obtained results have evidenced the formation of polyelectrolyte-colloid complexes of different structure upon the interaction of microbarite particles and the chains of polyanionic cellulose of different length, which results in the change in the rheological properties of the solutions.