PHYSICOCHEMICAL STUDIES ON XYLINAN (ACETAN) .2. CHARACTERIZATION BY STATIC LIGHT-SCATTERING

Laboratory-made samples of the polysaccharide xylinan, also called ace tan, were studied in aqueous solution at various ionic strengths I (0. 01 mol/L less than or equal to I less than or equal to 0.30 mol/L). Th e conditions for clarification (ultracentrifugation/membrane filtratio n) were studied. The Zimm procedure was used to obtain the average mol ar mass, the second virial coefficient, and the radius of gyration. Th e interpretation of the angular dependence of scattered Eight by fitti ng with ''Master Curves'' led to double-stranded wormlike chains with persistence lengths between 90 and 120 nm. The ionic strength had a st rong effect on the thermodynamic second virial coefficient, belt the o verall structure remained unchanged. The ambiguity of the light scatte ring data was dip cussed assuming alternatively a two-component system instead of the wormlike chain model for the experimental scattering c urves. The two-component system can be ruled out on the basis of model calculations. (C) 1996 John Wiley & Sons, Inc.