Yield stress and rheology of a self-associating chitosan solution
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We report that aqueous solutions of high molecular weight chitosan display a regime of shear thinning at low shear rates that is consistent with the existence of an apparent yield stress. The concentration-dependent scaling of the apparent yield stress, σ0(c)~c2.8±0.2 in the concentration range c = 7.50–65.0 mg/mL, is consistent with a solution microstructure of fractal clusters. Dynamic light scattering measurements at high concentration indicate extremely slow microdynamics, consistent with the presence of a structured network or glassy fluid. At shear rates above yielding, a constant viscosity plateau was observed with concentration-dependent scaling below the gel point consistent with existing models of entangled and associating polymers. The addition of urea, a hydrogen bond and hydrophobic interaction disrupter, did not change the reported concentration-dependent scaling of the apparent yield stress or the plateau viscosity but did weaken the apparent yield stress magnitude by ~ 30% on average.
KeywordsBiopolymer Flow-sensitive viscosity Yield stress Scattering Rheology Shear viscosity
The authors acknowledge Anton Paar for the availability of the MCR 702 Twin Drive rheometer through an instrument loan program.
Financial support for this research was provided by NSF (grant number NSF DMR 1408817).
- de Gennes P-G (1985) Scaling concepts in polymer physics, 2nd edn. Cornell University PressGoogle Scholar
- Hwang JK, Shin HH (2001) Rheological properties of chitosan solutions. Korea-Australia Rheol J 12:175–179Google Scholar
- Lapasin R, Pricl S (2012) Rheology of polysaccharide systems. In: Rheology of industrial polysaccharides: theory and applications. Springer Science & Business Media, pp 250–494Google Scholar
- Lucchesi L, Xie H (2015) Wound dressing devices and methodsGoogle Scholar
- Park JW, Park K-H (1983) Acid-base equilibria and related properties of chitosan. Bull Kor Chem Soc 4(2):68–72Google Scholar
- Rubinstein M, Colby RH (2003) Polymer physics, 1st edn, OxfordGoogle Scholar