Publication: Rheological study of the chitosan/glutaraldehyde chemical gel system
Authors
Argüelles Monal, W. ; Peniche Covas, C. ; Higuera Ciapara, I.
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Publisher
Elsevier
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DOI
https://doi.org/10.1016/S0966-7822(98)00032-X
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info:eu-repo/semantics/article
Description
©1998. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
This document is the Accepted, version of a Published Work that appeared in final form in Polymer Gels and Networks . To access the final edited and published work see https://doi.org/10.1016/S0966-7822(98)00032-X
Abstract
Chitosan dissolved in 0.1 mol l~1 acetic acid shows an apparent yield stress at very low frequencies, probably due to a structuring process yielding gel-like response. It re#ects complex relaxation mechanisms once chains disentangle and relax, presumably due to incipient hydrophobic contacts reinforced by the relative sti!ness of the chitosan chains, which tend to slow down reptation. When chemical cross-linkages are introduced, the weak self-associated network of chitosan is gradually replaced by a permanent covalent network as the molar ratio of aldehyde/amine groups, R, is increased. At R"0.4 a glass-to-rubber-type transition is observed, while at R"0.5 the form of the mechanical spectrum suggests the co-existence of a chemically cross-linked gel &dissolved' in a second entangled network formed by chitosan chains of restricted mobility. At higher cross-linking levels (R'1) a strong permanent gel is formed.
The observed frequency dependence near the rheological gel point suggests several modes of relaxation processes.
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Citation
Polymer Gels and Networks, 6, 1998: 429-440
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