Evaluation of thermo-viscosity parameters of dextran in polar and nonpolar solvent

Some thermo-viscosity parameters like Viscosity-molecular weight constant (K), the short-range parameter, (A) and long-range parameter (B) have been evaluated for the polymer "Dextran" of three different molecular weights ((M) over bar (omega) = 19,500, 75,000, and 250,000) in three different solvents like 6 (M) aqueous urea, 2 (M) aqueous glycine, and 50% aqueous glucose at temperatures ranging from 25 to 50 degreesC. The study reveals that the viscosity-molecular weight constant (K) decreases with increase in temperature for polar solvents like aqueous urea and aqueous glycine. The value of "K" increases with the rise in temperature within the range of 25 to 35 degreesC in case of a nonpolar solvent aqueous glucose and then "K" decreases with the increase in temperature within the range of 40 to 50 degreesC for the nonpolar solvent aqueous glucose. The short-range parameter (A) shows the same trend as shown by "K" and the long-range parameter "B" exhibits no definite trend with the variation of temperature. (C) 2001 John Wiley & Sons, Inc.