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The effect of ionic strength on the viscosity of sodium alginate solution
Author(s) -
Zhang Hucheng,
Wang Hanqing,
Wang Jianji,
Guo Ruifang,
Zhang Qingzhi
Publication year - 2001
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.97
Subject(s) - persistence length , ionic strength , viscosity , aqueous solution , ionic bonding , sodium , sodium alginate , materials science , intrinsic viscosity , thermodynamics , intermolecular force , chemistry , ion , molecule , organic chemistry , polymer , composite material , physics , metallurgy
The viscosities of aqueous sodium alginate solutions were measured in different NaCl concentrations (C s ) at 298 K. Based on the Odijk–Skolnick–Fixman theories, the electrostatic persistence lengths were calculated for various ionic strengths. The intrinsic persistence length of sodium alginate in solution was determined to be 125 Å by the method suggested by Odijk. In the region of $\hbox{C}_{\rm S}^{-1/2}> 6.5$ , the increase in intrinsic viscosity, [η], for sodium alginate on decreasing the C s is due to the larger contribution of electrostatic persistence length to the total persistence length, and the departure of [η] calc from [η] expl is attributed to the variation of the Flory Φ constant with ionic strength. A peak was observed in the plot of reduced viscosity v. sodium alginate concentration at a constant low ionic strength. As in the treatment of Rinaudo et al., this maximum in reduced viscosity is attributed to a preferential intermolecular distance. The roles of electrostatic persistence length, the critical inter‐rod spacing and the effect of added salt concentration on this maximum are discussed. Copyright © 2001 John Wiley & Sons, Ltd.