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Unusual rheology of a branched, water-soluble chitosan derivative

Naturevolume 302pages812814 (1983) | Download Citation



The rheological properties of polysaccharides are exploited for many industrial applications which have created an increasing demand for new inexpensive derivatives with improved performance1. N-Aklylation of the linear polysaccharide chitosan with various aldehydo-, keto- or lactone sugars affords branched-chain, water-soluble derivatives of high molecular weight for which the extent of branching as well as the branch conformation, length and type can readily be modified by appropriate choice of reagents and reaction conditions2. The products exhibit a correspondingly broad spectrum of rheological properties. We report here on some unusual non-newtonian features of one of these derivatives, 1-deoxylactit-1-yl chitosan, which displays low-shear newtonian behaviour, a medium-shear viscosity increase (dilatancy), and a high-shear viscosity drop (pseudoplasticity). In conditions of steady shear the shear stress-time function varies in the different shear rate regimes. A 2% solution of this derivative exhibits unique oscillatory behaviour under steady shear at the transition point between the dilatant and pseudoplastic regimes.

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    • Mansur Yalpani

    Present address: B. C. Research, Chemical Technology Division, 3650 Wesbrook Mall, Vancouver, British Columbia, Canada, V6S 2L2


  1. Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1W5

    • Mansur Yalpani
    •  & Donald E. Brooks
  2. Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1W5

    • Laurance D. Hall
    •  & Donald E. Brooks
  3. Department of Food Science, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1W5

    • Marvin A. Tung


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