Chain reorientation in ß-PVDF films upon transverse mechanical deformation stud...

• Autor(es): Barbosa, R. ; Mendes, J. A. ; Sencadas, V. ; Mano, J. F. ; Lanceros-Méndez, S.
• Data: 2003
• Identificador Persistente: http://hdl.handle.net/1822/3521
• Origem: RepositóriUM - Universidade do Minho
• Assunto(s): PVDF; SEM; Dielectric relaxation; Mechanical deformation
• Tipo de Documento: Artigo
• Idioma: Inglês

Descrição

Chain reorientation may be induced in polyvinylidene fluoride (PVDF) in its ß-phase by applying a deformation perpendicular to the pre-oriented polymeric chains. This reorientation begins right after the yielding point and seems to be completed when the stress-strain curve stabilizes. We have studied the chain reorientation mechanism by scanning electron microscopy (SEM) and dielectric relaxation methods and we have analyzed its influence in the alpha- and ß-relaxations of the polymer. SEM images confirm the existence of a reorientation upon transversal deformation. The decrease of crystallinity with increasing reorientation and the dependence of the dielectric permittivity upon deformation indicate that a model of stress-induced melting followed by an incomplete recrystallization properly describes the reorientation mechanism.