| Difference in concentration dependence of relaxation critical exponent N for alginate solutions at sol-gel transition induced by calcium cations. | |
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MedLine Citation:
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PMID: 16004457 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The sol-gel transition in aqueous alginate solutions induced by chelation with calcium cations from in situ release has been investigated with viscoelastic methods. Two alginate samples having different molecular weights (MW) were used over the concentration C(Alg) of 2 approximately 6 wt % with different mole ratio f of Ca2+ to the alginate repeat unit. The gel point f(gel) and relaxation critical exponent n were determined according to Winter's criterion, the later agrees well with that obtained from the relaxation modulus. The results indicate that the power law is valid for the dynamic relaxation at the gel point and the critical gel possesses the self-similarity in structure. With increasing C(Alg), f(gel) for the alginate with lower MW decreases dramatically and n is almost constant of about 0.71. In contrast, f(gel) for the higher MW alginate with is almost a constant and n decreases from 0.72 then levels off at 0.37 with increasing C(Alg), indicating that the concentration dependence of n varies with MW of alginate in the starting solution. The fractal dimension d(f) estimated from n suggests a denser structure in the critical gel of higher MW alginate. Either n or d(f) has been found to follow one curve for the two samples if plotted against the number of cross-link junctions per polymer chain, which is proportional to the alginate MW. |
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Authors:
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Lu Lu; Xinxing Liu; Lin Dai; Zhen Tong |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biomacromolecules Volume: 6 ISSN: 1525-7797 ISO Abbreviation: Biomacromolecules Publication Date: 2005 Jul-Aug |
Date Detail:
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Created Date: 2005-07-11 Completed Date: 2005-11-14 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 100892849 Medline TA: Biomacromolecules Country: United States |
Other Details:
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Languages: eng Pagination: 2150-6 Citation Subset: IM |
Affiliation:
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Research Institute of Materials Science, South China University of Technology, Guangzhou 510640, China. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Alginates
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chemistry* Calcium / chemistry* Cations Gels / chemistry* Rheology Solutions |
| Chemical | |
Reg. No./Substance:
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0/Alginates; 0/Cations; 0/Gels; 0/Solutions; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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