Dielectric and Molecular Dynamics Study of the Secondary Relaxations of Poly(styrene-co-methylmethacrylate) Copolymers: Influence of the Molecular Architecture

Encinar, M. y Prolongo, M.G. . (2011) Dielectric and Molecular Dynamics Study of the Secondary Relaxations of Poly(styrene-co-methylmethacrylate) Copolymers: Influence of the Molecular Architecture. European Physical Journal E (v. 34), 2011, pp. 134-1/14 ISSN: 1292-8941, EISSN: 1292-895X doi: 10.1140/epje/i2011-11134-4

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Título Dielectric and Molecular Dynamics Study of the Secondary Relaxations of Poly(styrene-co-methylmethacrylate) Copolymers: Influence of the Molecular Architecture
Autor(es) Encinar, M.
Prolongo, M.G.
Materia(s) Física
Química
Resumen The effect of the structure of copolymers (random, alternate or diblock) on their dynamics has been studied by dielectric spectroscopy. Six copolymers of styrene and methyl methacrylate (three diblocks, one alternate and two random) have been studied. The results show that the sub-Tg transitions of the diblock samples can be described by one asymmetric Havriliak-Negami (HN) function, while two are necessary for the rest of the copolymers (β and γ relaxations). The characteristic times of the sub-Tg relaxations show an Arrhenius temperature dependence and there is a strong coupling of the α and β relaxations at high temperatures. The deconvolution of the merging relaxations has been made in the framework of the Williams Ansatz set out in terms of Havriliak-Negami distributions. The γ relaxation may be assigned to the rotation of the methyl methacrylate group in a styrene-rich environment. The Molecular Dynamics simulations of a poly(methyl methacrylate) homopolymer and of the alternate copolymer are in qualitative agreement with the experimental results, although they predict smaller values for the activation energy of the sub-Tg relaxations.
Editor(es) EDP Sciences ; Springer Verlag (Germany) ; Società Italiana di Fisica
Fecha 2011-11-07
Formato application/pdf
Identificador bibliuned:DptoCTFQ-FCIE-MODELICO-1015
http://e-spacio.uned.es/fez/view/bibliuned:DptoCTFQ-FCIE-MODELICO-1015
DOI - identifier 10.1140/epje/i2011-11134-4
ISSN - identifier 1292-8941, EISSN: 1292-895X
Publicado en la Revista European Physical Journal E (v. 34), 2011, pp. 134-1/14 ISSN: 1292-8941, EISSN: 1292-895X doi: 10.1140/epje/i2011-11134-4
Idioma eng
Versión de la publicación acceptedVersion
Relacionado con el proyecto: info:eu-repo/grantAgreement/S2009/ESP-1691
Tipo de recurso Article
Derechos de acceso y licencia http://creativecommons.org/licenses/by-nc-nd/4.0
info:eu-repo/semantics/openAccess
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Creado: Wed, 03 Sep 2014, 14:19:27 CET