Hydrodynamic properties of amylose acetate in nitromethane

Abstract

Viscosity, light-scattering and sedimentation studies have been made on nitromethane solutions of acetylated fractions of linear amylose. The following relations were obtained : [η]= 8.50 × 10^–3M^0.73_W; (r²)= 1.95 × 10^–17M^1.16_W; and S_o= 2.25 × 10^–15M^0.42_W. The exponents in these relations are those expected from the Flory theory. From the calculated values of the viscosity constantϕ it was not possible to distinguish between the Flory model and its modifications proposed by Kurata and Stockmayer. Unperturbed dimensions have been calculated using the experimental radius of gyration and the second virial coefficient. Comparison of the unperturbed dimensions with those calculated on the basis of free rotation indicates that the monomer units may exist in a boat conformation. The length of the Kuhn statistical segment was 65 Å comparison of the hydrodynamic parameters for amylose acetate and cellulose acetate indicates little similarity.