SEDIMENTATION ANALYSIS OF AGAR MOLECULE

To clear the molecular-weight distribution of 6 kinds of agar molecule s and the stiffness of the molecule in hot solution with hydrodynamic model, sedimentation velocity measurement was performed. Distribution of the sedimentation constant of agar molecules showed broad and asymm etrical curves in all samples. According to the theories of Yamakawa e t al. for a cylindrical wormlike chain model, the translational fricti on coefficient and the intrinsic viscosity were approximated. The excl uded volume also was estimated by use of the second virial coefficient . From the combination of the persistence length with the excluded vol ume, agar molecular chain showed the behavior of a typical flexible ch ain; the chain of higher molecular weight was flexible, and that the l ower one was relatively rigid in the hot aqueous solution. It was pred icted that the properties of the commercial agar-gel did not simply de pend on the average molecular weight and that the flexibility of the c hain had an effect on the gel strength.