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|Title:||Chain reorientation in ß-PVDF films upon transverse mechanical deformation studied by SEM and dielectric relaxation|
Mendes, J. A.
Sencadas, Vítor João Gomes Silva
Mano, J. F.
|Publisher:||Taylor and Francis|
|Citation:||"Ferroelectrics". ISSN 0015-0193. 294 (2003) 78-83.|
|Abstract(s):||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.|
|Appears in Collections:||CDF - FCD - Artigos/Papers (with refereeing)|