Effect of crystallization temperature on the phase transitions of P(VDF/TrFE) copolymers

Effect of crystallization temperature on the phase transitions of P(VDF/TrFE) copolymers

Autor Gregorio, R. Google Scholar
Botta, M. M. Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Resumo A systematic study was carried out on the effect of the crystallization temperature (T-cr,,), on the phase transitions presented by P(VDF/TrFE) copolymers cast from dimethylformamide (DMF) solution with molar ratios 60/40, 70/30, and 80/20. the results obtained by differential scanning calorimetry (DSC) showed that two-phase transitions are observed only when the copolymer crystallizes above a certain temperature T-o,, and that the temperatures at which these transitions occur are reduced slightly with T-cr,, increase. It also was observed that when T-cr,, increases, the intensity of the endotherm corresponding to the lowest temperature transition is increased, whereas the one corresponding to the highest temperature transition is reduced. in order to explain these phenomena, the existence of two ferroelectric and two paraelectric phases is suggested. the conformational differences between like phases occur due to the distinct origin of each one: the best organized phase crystallizes directly from solution, whereas the least organized is the result of a solid phase transition. Wide angle x-ray diffusion(WAXD) diffractograms corroborate this hypothesis. Phase diagrams for samples crystallized below and above T-o, have been proposed. (C) 1998 John Wiley & Sons, Inc.
Palavra-chave P(VDF/TrFE) copolymer
phase transition
ferroelectric
crystallization
Idioma Inglês
Data de publicação 1998-02-01
Publicado em Journal of Polymer Science Part B-polymer Physics. New York: John Wiley & Sons Inc, v. 36, n. 3, p. 403-414, 1998.
ISSN 0887-6266 (Sherpa/Romeo, fator de impacto)
Publicador Wiley-Blackwell
Extensão 403-414
Fonte http://dx.doi.org/10.1002/(SICI)1099-0488(199802)36:3<403
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000071815900002
Endereço permanente http://repositorio.unifesp.br/handle/11600/25858

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