| Research Abstract |
Three types of Gellan Gum aqueous solutions were studied, in which Ca^<2+>-contents were controlled to (i) <<0.01wt% and (ii)*0.5wt%, and the replacement of Na^+ toK^+was performed by ion-exchange resin.In the case of (i), abrupt decreasings in viscosity in the temperature range of <plus-minus>0.5ﾟC were observed, and we assumed that this may be caused by Helix-Coil transition of Gellan Gum molecules. In the case of K-type Gellan Gum, viscosity of solutions decrease as the temperature was raised, through the maximum point of viscosity. Hyaluronic acid aqueous solutions, of which two types of molecular weight, 1.0*10^6 and 2.0*10^6 and four kinds of concentration of 1.0,0.75,0.5 and 0.25 wt% were studied in the period of 360-23,040s. J_1 (omega lambda), J_2 (omega lambda)-In (omega lambda) plot of these solutions were nearly expressed by Voigt model, here J^*(complex compliance) =J_1-i・J_2 in the whole concentration range. In the case of Cole-Cole plot (J^*=alpha[1/{1+(iomega lambda)beta}], all observed points could be expressed as an arc with beta=0.725.This means that distribution of retardation time should be taken into consideration of viscoelastic behaviors of Hyaluronic acid aqueous solutions.
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