STRUCTURAL-MECHANICAL (RHEOLOGICAL) PROPERTIES OF A GEL BASED ON POLYVINYL ALCOHOL

In this work, the structural-mechanical (rheological) properties of a gel-forming system containing polyvinyl alcohol (gelling agent) and an alkaline composition based on an inorganic buffer system and a polyol (cross-linking agent) were studied. Rheological measurements were carried out on a Haake Viscotester iQ rheometer equipped with a CC25 coaxial cylinder measuring system. Temperature control was carried out by a Peltier element built into the rheometer. In the oscillatory mode, at a rotor oscillation frequency of 1 Hz, amplitude sweeps were obtained for the gel formed from the initial compositions, and the LVE range was determined. Then, in the strain-controlled mode, at a strain value of 0.1 from the range of linear viscoelasticity, the kinetic dependences were obtained for the elastic modulus G', loss modulus G'' and complex viscosity |η*| for compositions that differ in the ratio of crosslinker components at room temperature. It was shown that in all studied systems, at the initial moments of time, a sharp increase in rheological characteristics is observed - a gel begins to form already at the moment of mixing the components. Further, over time, the rate of increase in G', G'' and |η*| decreases, and the rheokinetic curves reach an almost horizontal section - a three-dimensional structure - a gel - is formed in the entire volume of the sample. It was found that the recorded curves change symbatically under experimental conditions, and the ratio of the components of the complex module is related to the concentration of the crosslinker. For a composition with an increased crosslinker concentration, the elastic properties of the emerging structure predominate (G' > G''), while, compared to a less concentrated crosslinker composition, the strength of the structure increases, and the recorded values of the components of the complex modulus differ by an order of magnitude. For citation: Kozhevnikov I.S., Fufaeva M.S. Structural-mechanical (rheological) properties of a gel based on polyvinyl alcohol. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 8. P. 20-25. DOI: 10.6060/ivkkt.20256808.4t.