Viscoelasticity of a Nonionic Lamellar Phase

Detalhes bibliográficos
Autor(a) principal: Medronho, B.
Data de Publicação: 2007
Outros Autores: Miguel, Maria G., Olsson, U.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10316/10497
https://doi.org/10.1021/la063599a
Resumo: The linear viscoelastic properties of a nonionic lamellar phase in C-orientation were studied as a function of temperature by small-amplitude oscillatory measurements in the frequency range 0.5−5 Hz. An almost solidlike elastic response was observed at all studied temperatures, from 42 to 20 °C. In this range, the elastic modulus was found to increase strongly with decreasing temperature. The elasticity is attributed to screw dislocations connecting layers in the stack, and the data thus suggest that the density of screw dislocations decreases with increasing temperature. The lamellar phase forms an “onion” texture when continuously sheared at lower temperatures. It is argued that a possible origin for the shear-induced “onion” texture is the instability of the screw dislocations in shear flow. By 2H NMR experimentation, we also find the formation of a random mesh phase at lower temperatures. The presence of equilibrium bilayer perforations, however, does not correlate with the “onion” stability.
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spelling Viscoelasticity of a Nonionic Lamellar PhaseThe linear viscoelastic properties of a nonionic lamellar phase in C-orientation were studied as a function of temperature by small-amplitude oscillatory measurements in the frequency range 0.5−5 Hz. An almost solidlike elastic response was observed at all studied temperatures, from 42 to 20 °C. In this range, the elastic modulus was found to increase strongly with decreasing temperature. The elasticity is attributed to screw dislocations connecting layers in the stack, and the data thus suggest that the density of screw dislocations decreases with increasing temperature. The lamellar phase forms an “onion” texture when continuously sheared at lower temperatures. It is argued that a possible origin for the shear-induced “onion” texture is the instability of the screw dislocations in shear flow. By 2H NMR experimentation, we also find the formation of a random mesh phase at lower temperatures. The presence of equilibrium bilayer perforations, however, does not correlate with the “onion” stability.American Chemical Society2007-05-08info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://hdl.handle.net/10316/10497http://hdl.handle.net/10316/10497https://doi.org/10.1021/la063599aengLangmuir. 23:10 (2007) 5270-52740743-7463Medronho, B.Miguel, Maria G.Olsson, U.info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2021-09-28T08:29:45Zoai:estudogeral.uc.pt:10316/10497Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T21:01:31.971008Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Viscoelasticity of a Nonionic Lamellar Phase
title Viscoelasticity of a Nonionic Lamellar Phase
spellingShingle Viscoelasticity of a Nonionic Lamellar Phase
Medronho, B.
title_short Viscoelasticity of a Nonionic Lamellar Phase
title_full Viscoelasticity of a Nonionic Lamellar Phase
title_fullStr Viscoelasticity of a Nonionic Lamellar Phase
title_full_unstemmed Viscoelasticity of a Nonionic Lamellar Phase
title_sort Viscoelasticity of a Nonionic Lamellar Phase
author Medronho, B.
author_facet Medronho, B.
Miguel, Maria G.
Olsson, U.
author_role author
author2 Miguel, Maria G.
Olsson, U.
author2_role author
author
dc.contributor.author.fl_str_mv Medronho, B.
Miguel, Maria G.
Olsson, U.
description The linear viscoelastic properties of a nonionic lamellar phase in C-orientation were studied as a function of temperature by small-amplitude oscillatory measurements in the frequency range 0.5−5 Hz. An almost solidlike elastic response was observed at all studied temperatures, from 42 to 20 °C. In this range, the elastic modulus was found to increase strongly with decreasing temperature. The elasticity is attributed to screw dislocations connecting layers in the stack, and the data thus suggest that the density of screw dislocations decreases with increasing temperature. The lamellar phase forms an “onion” texture when continuously sheared at lower temperatures. It is argued that a possible origin for the shear-induced “onion” texture is the instability of the screw dislocations in shear flow. By 2H NMR experimentation, we also find the formation of a random mesh phase at lower temperatures. The presence of equilibrium bilayer perforations, however, does not correlate with the “onion” stability.
publishDate 2007
dc.date.none.fl_str_mv 2007-05-08
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
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status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10316/10497
http://hdl.handle.net/10316/10497
https://doi.org/10.1021/la063599a
url http://hdl.handle.net/10316/10497
https://doi.org/10.1021/la063599a
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv Langmuir. 23:10 (2007) 5270-5274
0743-7463
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dc.publisher.none.fl_str_mv American Chemical Society
publisher.none.fl_str_mv American Chemical Society
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