Viscoelastic Properties of Hyaluronic Aqueous Solutions.
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概要
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Viscoealstic properties of hyaluronic acid (HA) aqueous solutions were studied in the range of <I>C</I><SUB>p</SUB> (polymer concentration) =1.0-0.25 wt% and <I>T</I>/s (period) =180-23040 at 36.0°C by a magnetic rheometer, which was newly constructed in our laboratory. The behavior was tried to express with a simple mechanical model, and by adopting the value of (a) <I>C</I><SUB>p</SUB>/wt%=1.0, <<<I>J</I><SUB>1.0</SUB>>>/Pa<SUP>-1</SUP>=68.0 (mean value of <I>T</I>/s=2880-23040), (b) <I>C</I><SUB>p</SUB>/wt%=0.75, <<<I>J</I><SUB>0.75</SUB>>>/Pa<SUP>-1</SUP>=67.9 (mean value of <I>T</I>/s=1440-11520), (c) <I>C</I><SUB>p</SUB>/wt%=0.5, <<<I>J</I><SUB>0.5</SUB>>>/Pa<SUP>-1</SUP>=68.7 (mean value of <I>T</I>/s=360-11520), and (d) <I>C</I><SUB>p</SUB>/wt%=0.25, <<<I>J</I><SUB>0.25</SUB>>>/Pa<SUP>-1</SUP>=80.5 (mean value of <I>T</I>/s=360-11520), dispersion curves for Na-type HA aqueous solutions could be well expressed by a Voigt model in the above range of the concentrations and periods. The Cole-Cole plot of <I>f</I><SUB>1</SUB>= [<<I>J</I><SUB><I>i, T</I></SUB>>/ (1+ω<SUP>2</SUP>λ<SUP>2</SUP>)] against <I>f</I><SUP>2</SUP>= [<<I>J</I><SUB><I>i, T</I></SUB>>·ωλ/ (1+ω<SUP>2</SUP>λ<SUP>2</SUP>)] was also tried with the values of (a) <<<I>J</I><SUB>1.0</SUB>>>/Pa<SUP>-1</SUP>=68.0 (<I>C</I><SUB>p</SUB>/wt%=1.0), β=0.725, and (b) <<<I>J</I><SUB>0.5</SUB>>>/Pa<SUP>-1</SUP>=68.7 (<I>C</I><SUB>p</SUB>/wt%=0.5), β=0.725, and the observed values fitted with these calculated curves. Na<SUP>+</SUP> ion in Na-type HA was replaced by M<SUP>+</SUP> alkaline ion (Li<SUP>+</SUP>, K<SUP>+</SUP>, or Cs<SUP>+</SUP>) by passing through ion exchange resins. In the case of K-type HA solutions, viscosities decreased by two orders from those of Na-type HA solutions, but rigidities did not change so much. Viscosities of the solutions decreased in the order of Na<SUP>+</SUP>, Li<SUP>+</SUP>, K<SUP>+</SUP>, and Cs<SUP>+</SUP>, differing from the order of alkaline-ion series. Activation energies of viscous flow were found as ≅ 30 kJ mol<SUP>-1</SUP> for each solution, which is nearly equal to that of hydrogen bond energy.
- 公益社団法人 高分子学会の論文
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