Heteroxylans from maize bran in aqueous solution. II. Studies of polyelectrolyte behaviour
1997
Chanliaud, E. | Saulnier, L. | Thibault, J.F.
Potentiometric and viscosimetric behaviours of four samples of heteroxylans, extracted from corn bran at different temperatures with varying type and concentration of alkali were studied in dilute solutions. All four samples behave as typical polyelectrolytes with a low charge density parameter (gamma = 0.15). They could be described by the Lifson and Katchalsky model (pK0 approximately equal to 3.15), indicating a rather homogeneous repartition of the charges along the macromolecules. Their intrinsic viscosities varied linearly with the reciprocal of the square root of the ionic strength. Their flexibility parameters, B (approximately equal to 0.024), were similar to those of semi-flexible macromolecules, and their intrinsic viscosities extrapolated to infinite ionic strength were between 144 and 177 ml/g. Their conformational dimensions depended on the type of counter-ion in solution (dimensions minimal with divalent cations and decreasing with size of monovalent alkali metal ions), of the temperature and the pH of the solution. The radius of gyration for unchanged heteroxylans was estimated from intrinsic viscosities extrapolated to infinite ionic strength (< R(2)g infinity > 1/2 = 21-25 nm).
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