Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity
Autor(a) principal: | |
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Data de Publicação: | 2005 |
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/1822/14157 |
Resumo: | Poly(L-lactic acid), PLLA, in amorphous and semi-crystalline forms were studied by DSC, in order to investigate both molecular dynamics and structural relaxation features, and to understand the influence of the crystalline confinement on the segmental mobility of the intraspherulitic amorphous phase. Experimental data were generated after submitting the materials to different thermal histories below Tg and were treated with a model based on the configurational entropy concept, allowing to extract a series of physical-meaningful parameters and to obtain the temperature dependence of the relaxation times. The main features of the relaxation process in the glassy state (activation energy of the glassy state and x) and the fragility index were found to be apparently insensitive to crystallinity. Significant differences between the two materials were detected in both the position of the glass transition temperature and the width of the distribution of relaxation times. In the framework of the Adam and Gibbs theory, it is suggested that for the semi-cristalline PLLA the mobility of the amorphous chains is more or less restricted, depending on their distance to the rigid lamellar walls or on the intra-lamellar thickness; this will imply that their conformational motions will take place at different temperatures, typically above the glass transition temperature of the (unconfined) bulk amorphous phase. |
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Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinitySemi-crystalline polyestersPolylactidesGlass transitionScience & TechnologyPoly(L-lactic acid), PLLA, in amorphous and semi-crystalline forms were studied by DSC, in order to investigate both molecular dynamics and structural relaxation features, and to understand the influence of the crystalline confinement on the segmental mobility of the intraspherulitic amorphous phase. Experimental data were generated after submitting the materials to different thermal histories below Tg and were treated with a model based on the configurational entropy concept, allowing to extract a series of physical-meaningful parameters and to obtain the temperature dependence of the relaxation times. The main features of the relaxation process in the glassy state (activation energy of the glassy state and x) and the fragility index were found to be apparently insensitive to crystallinity. Significant differences between the two materials were detected in both the position of the glass transition temperature and the width of the distribution of relaxation times. In the framework of the Adam and Gibbs theory, it is suggested that for the semi-cristalline PLLA the mobility of the amorphous chains is more or less restricted, depending on their distance to the rigid lamellar walls or on the intra-lamellar thickness; this will imply that their conformational motions will take place at different temperatures, typically above the glass transition temperature of the (unconfined) bulk amorphous phase.ElsevierUniversidade do MinhoMano, J. F.Gómez Ribelles, J. L.Alves, N. M.Salmerón-Sánchez, M.2005-092005-09-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/1822/14157eng0032-386110.1016/j.polymer.2005.06.096Doi:10.1016/j.polymer.2005.06.096info: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:RCAAP2023-07-21T12:11:59Zoai:repositorium.sdum.uminho.pt:1822/14157Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T19:03:52.704446Repositório 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 |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
title |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
spellingShingle |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity Mano, J. F. Semi-crystalline polyesters Polylactides Glass transition Science & Technology |
title_short |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
title_full |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
title_fullStr |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
title_full_unstemmed |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
title_sort |
Glass transition dynamics and structural relaxation of PLLA studied by DSC : Influence of crystallinity |
author |
Mano, J. F. |
author_facet |
Mano, J. F. Gómez Ribelles, J. L. Alves, N. M. Salmerón-Sánchez, M. |
author_role |
author |
author2 |
Gómez Ribelles, J. L. Alves, N. M. Salmerón-Sánchez, M. |
author2_role |
author author author |
dc.contributor.none.fl_str_mv |
Universidade do Minho |
dc.contributor.author.fl_str_mv |
Mano, J. F. Gómez Ribelles, J. L. Alves, N. M. Salmerón-Sánchez, M. |
dc.subject.por.fl_str_mv |
Semi-crystalline polyesters Polylactides Glass transition Science & Technology |
topic |
Semi-crystalline polyesters Polylactides Glass transition Science & Technology |
description |
Poly(L-lactic acid), PLLA, in amorphous and semi-crystalline forms were studied by DSC, in order to investigate both molecular dynamics and structural relaxation features, and to understand the influence of the crystalline confinement on the segmental mobility of the intraspherulitic amorphous phase. Experimental data were generated after submitting the materials to different thermal histories below Tg and were treated with a model based on the configurational entropy concept, allowing to extract a series of physical-meaningful parameters and to obtain the temperature dependence of the relaxation times. The main features of the relaxation process in the glassy state (activation energy of the glassy state and x) and the fragility index were found to be apparently insensitive to crystallinity. Significant differences between the two materials were detected in both the position of the glass transition temperature and the width of the distribution of relaxation times. In the framework of the Adam and Gibbs theory, it is suggested that for the semi-cristalline PLLA the mobility of the amorphous chains is more or less restricted, depending on their distance to the rigid lamellar walls or on the intra-lamellar thickness; this will imply that their conformational motions will take place at different temperatures, typically above the glass transition temperature of the (unconfined) bulk amorphous phase. |
publishDate |
2005 |
dc.date.none.fl_str_mv |
2005-09 2005-09-01T00:00:00Z |
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/1822/14157 |
url |
http://hdl.handle.net/1822/14157 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
0032-3861 10.1016/j.polymer.2005.06.096 Doi:10.1016/j.polymer.2005.06.096 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Elsevier |
publisher.none.fl_str_mv |
Elsevier |
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 |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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1799132446605705216 |