Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.14/5459
Título: Influence of temperature on the dynamic and steady-shear rheology of pectin dispersions
Autor: Silva, J. A. Lopes da
Gonçalves, M. P.
Rao, M. A.
Data: 1994
Editora: Elsevier
Citação: SILVA, J. A. Lopes da ; GONÇALVES, M. P. ; RAO, M. A. - Influence of temperature on the dynamic and steady-shear rheology of pectin dispersions. Carbohydrate Polymers. ISSN 0144-8617. Vol. 23, n.º 2 (1994), p. 77-87
Resumo: The influence of temperature on the dynamic and steady-shear rheology of ionic polysaccharides, high-methoxyl and low-methoxyl pectins, has been studied and compared with the behaviour of locust bean gum, a virtually neutral biopolymer. Using the time-temperature superposition principle, the rheological parameters were reduced to an arbitrary reference temperature. Activation energies were calculated and their dependence on temperature and shear rate analysed. Concerning the viscosity dependence on temperature, two approaches have been considered: one associated with the theory of absolute reaction rates leading to an Arrhenius type equation, and the other associated with the free volume theory, expressed by the Williams-Landel-Ferry equation. The difficulties encountered in the superposition of the dynamic properties of the pectin dispersions, the high activation energies, yield values and elastic plateau at low oscillatory frequency, are consistent with a macromolecular organization of these polymers dominated by important aggregation phenomena, which could be attributed to important intermolecular interactions like hydrogen bonding and hydrophobic interactions, especially in conditions of low degree of ionization of the carboxylic groups.
Peer review: yes
URI: http://hdl.handle.net/10400.14/5459
Versão do Editor: http://www.sciencedirect.com/science/article/pii/0144861794900310
Aparece nas colecções:ESB - Artigos em revistas internacionais com Arbitragem / Papers in international journals with Peer-review

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