Molecular dynamics simulations of α- to β-poly(vinylidene fluoride) phase change by stretching and poling

Crystalline polymorphism in poly(vinylidenefluoride) membranes

“…The transformation procedure is described in Table 7. The molecular simulation showed that the direction of poling plays a key role in the structure of the induced phase [25], because only poling in the x direction provided a structure that was similar to the β PVDF crystal, although poling in both the x and y directions (perpendicular to the molecular chains) yielded a polar crystal structure. In this sense, poling increases mechanical strength along the longitudinal direction and basically does not affect the transversal direction.…”

“…It is for this reason that β PVDF has the best piezoelectric, pyroelectric, and ferroelectric properties. In α PVDF crystals, chains are aligned anti-parallel to each other, resulting in nonpolar crystal structures [25]. In the α and γ phases, the crystal structure can adopt either orthorhombic or monoclinic modifications, depending on whether the chains are statistically packed or not [26].…”

Electric field poling 2G V/m to improve piezoelectricity of PVDF thin film

“…Based on XRD characterization of the samples then conducted the calculations of fraction of PVDF film sample using equation (6). (6) The fraction of PVDF films for different annealing temperatures before and after poling are expressed in Table 1.…”

“…The study of the transformation of the structure of PVDF has been widely studied among others by previous researchers. Recently, many research focuses on increasing the amount of the β -phase in PVDF to obtain a good piezoelectric and pyroelectric material [4,5,6,7,8,9].…”

An improved process for polyvinylidene fluoride membrane preparation by using a water soluble diluent via thermally induced phase separation technique

“…The PVDF membrane precipitated in coagulation bath at 60℃ has a typical  form crystal structure, while the PVDF crystallites are a mixture of  and  form crystal structures at 15℃ [31]. The crystal structure of PVDF membrane rearranges from mainly  form crystallites to mainly  form crystallites with increasing DMAc content in coagulation bath [32] or by stretching membrane [33]. [29,34].…”