A.Martinez-Ruvalcaba, E. Chornet, D. Rodrigue
Dynamic rheological properties of concentrated Chitosan solutions
Appl. Rheol. 14:3 (2004) 140-147Abstract: A detailed analysis of the dynamic flow properties of chitosan in solution at different temperatures (25 - 45 C), chitosan concentration (0.5% - 2.0%), solvent type (acetic, lactic, and hydrochloric acid), and ionic strength (0 and 0.2M NaCl) has been undertaken. The storage modulus, G', loss modulus, G'' and complex viscosity, h* have been determined over a wide range of frequencies and the results are presented using master curves. For the conditions studied, at low frequencies chitosan solutions show a constant complex viscosity which decreases as frequency increases. Likewise, storage modulus, G' and loss modulus, G'' increase as frequency increases with G'' being always greater than G' indicating that viscous effects are more important than elastic effects. For modelling the oscillatory-shear results we used the generalized Maxwell model. Two empirical equations were used to correlate the data: Cox-Merz rule for viscosity and Laun's rule for primary normal stress difference. Both relations were found to represent our data for the experimental conditions studied. © 2004 Applied Rheology.
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