Viscoelasticity of a Nonionic Lamellar Phase
Autor(a) principal: | |
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Data de Publicação: | 2007 |
Outros Autores: | , |
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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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 |
format |
article |
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 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
American Chemical Society |
publisher.none.fl_str_mv |
American Chemical Society |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
repository.mail.fl_str_mv |
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1817552770288320512 |