Activation enthalpy of diffusion for well fractionated dextrans in aqueous solutions.
Interdiffusion coefficients have been determined for seven well defined dextran fractions in aqueous solutions at 20, 25, 30 and 35 degrees C. For dextrans with number average molecular weights (Mn) greater than about 20 000, a plot of the apparent activation energy of diffusion (ED) against Mn is given by: ED = 2.763 x 10(-5) Mn + 3.38. Similarly, for weigh molecular weight (Mw): ED = 1.889 x 10(-5) Mw + 3.61. The extrapolated ED values (3.38 and 3.61) are in reasonably good agreement with published data for the activation energy of self-diffusion for water.
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Institute of Physical Chemistry, University of Uppsala, Box 532, S-751 21 Uppsala 1, Sweden.