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Synthesis and Flow Behavior of Sodium Carboxymethyl Starch: A Study on Viscosity and Rheology

M. A. MakhkamovNational University of Uzbekistan named after Mirzo Ulugbek , Tashkent , 100174 , UzbekistanS. Y. SaparovInstitute of Pharmaceutical Education and Research , Tashkent , 100114 , UzbekistanIslomjon KhudoyberdiyevNational University of Uzbekistan named after Mirzo Ulugbek , Tashkent , 100174 , UzbekistanI. B. GulomovaNational University of Uzbekistan named after Mirzo Ulugbek , Tashkent , 100174 , UzbekistanR. S. EsanovInstitute of Bioorganic Chemistry AS RUz , Tashkent , 100125 , UzbekistanA. D. MatchanovInstitute of Bioorganic Chemistry AS RUz , Tashkent , 100125 , UzbekistanF A SobirovaAlfraganus University , Tashkent , 100190 , UzbekistanElmira O. AimbetovaInstitute of Ecological Problems , Al-Farabi Kazakh National University , Al-Farabi Ave. 71 , Almaty , 050040 , Kazakhstan

2025en

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ABI

Annotatsiya

By chemically modifying starch in the solid phase, samples of the sodium carboxymethyl starch (Na-CMS) with degrees of substitution (DS) ranging from 0.09 to 0.95 were obtained.The viscosity of both dilute and concentrated aqueous Na-CMS solutions was analyzed using capillary and rotational viscometry.It has been shown that diluted Na-CMS solutions exhibit properties characteristic of polyelectrolytes.The rheological properties were investigated by varying the shear rate across a broad temperature range.The results indicate that concentrated Na-CMS solutions exhibit non-Newtonian behavior at all studied temperatures.The dynamic viscosity of Na-CMS solutions decreases with increasing DS, suggesting a reduction in intermolecular interactions.An increase in temperature also leads to a marked decrease in the dynamic viscosity of Na-CMS solutions.For example, for Na-CMS solutions with DS=0.74, increasing the temperature from 25 to 55 °C leads to a decrease in viscosity from 10.3 to 5.1 Pas.The average value of the activation energy of the viscous flow of Na-CMS solutions was determined, which is equal to 18.7 kJ/mol, indicating the presence of hydrogen bonds between polymer macromolecules.

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DOI: 10.30919/faf1530

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