抄録
We have investigated the electric conductivity and dielectric constant of an aqueous solution of polysaccharide, Aphanothece sacrum, that is called sacran. The molar conductivity at high concentrations obeyed Kohlrausch's law. The equivalent conductivity at infinite dilution was in good agreement with that of Na+ ion in an aqueous solution. The complex dielectric constant ε* of the aqueous solutions was measured from 42Hz to 5 MHz by an ac two-terminals method. The dielectric spectra of the aqueous solutions after subtracting the electrode polarization effect could be fitted by two Debye type relaxations. The low frequency relaxation and high frequency one appeared at 100Hz and 100kHz, respectively. The low frequency relaxation time for the aqueous solution of 2.0×10-3 wt.% was determined to be 2.1×10-3 s. The contour length of the sacran was estimated to be ～5.5 μm using the diffusion constant of Na+ ion in a free medium. This value was in the same magnitude with the length evaluated from transmission electron microscopy and static light scattering experiments.
