Publication series : Biological Activities and Application of Marine Polysaccharides
Author: Andrea Rivera del Rio Mariana Ramírez-Gilly and Alberto Tecante
Publisher: IntechOpen
Publication year: 2017
E-ISBN: INT6275265785
P-ISBN(Paperback): 9789535128595
P-ISBN(Hardback): 9789535128601
Subject: Q5 Biochemistry
Keyword: 生物化学
Language: ENG
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Flow Properties of Lambda Carrageenan in Aqueous Systems
Description
Small amplitude oscillatory and steady shear measurements at 25°C were used to investigate the rheological behavior of λ‐carrageenan solutions at pH 7.0 ± 1.0 without and with added sodium counterion. The dynamic moduli, G′(ω) and G″(ω), show the typical behavior of macromolecular solutions in which the viscous character predominates. The steady shear flow exhibits a Newtonian zero‐shear viscosity (η0) region followed by a shear‐thinning zone. Viscosity data can be well described by the Carreau‐Yasuda model. Without added Na+, the intrinsic viscosity, [η], and the critical overlap concentration, C*, are 204 dL/g and 0.21%, respectively. With 20 mmol/dm3 Na+, [η] = 14.7 dL/g and C* = 0.38%. For concentrations below C*, the viscous character is more sensitive to the presence of added Na+, and the opposite occurs when the concentration exceeds C*. The dynamic moduli and viscosity increase with the increase of polysaccharide concentration, but they decrease with added Na+, confirming the polyelectrolyte nature of λ‐carrageenan. Empirical shift factors were used to obtain master curves for the dynamic moduli and apparent viscosity for different polysaccharide and added Na+ concentrations.
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