Abstract
To clear the molecular-weight distribution of 6 kinds of agar molecules 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 asymmetrical curves in all samples. According to the theories of Yamakawa et al. for a cylindrical wormlike chain model, the translational friction coefficient and the intrinsic viscosity were approximated. The excluded volume also was estimated by use of the second virial coefficient. From the combination of the persistence length with the excluded volume, agar molecular chain showed the behavior of a typical flexible chain; the chain of higher molecular weight was flexible, and that the lower one was relatively rigid in the hot aqueous solution.
It was predicted that the properties of the commercial agar-gel did not simply depend on the average molecular weight and that the flexibility of the chain had an effect on the gel strength.
