Polyvinyhdene fluoride, PVDF

Besides binary composites consisting of only one polymer component and the carbon nanotubes, the use of ternary or even quaternary mixtures was also found useful in some cases. There is, for instance, a composite of polymethacrylate with carbon nanotubes previously treated with polyvinyhdene fluoride (PVDF). It is obtained by melt blending. There may be no covalent bonding between nanotubes and methacrylate, the coating with the significantly less polar PVDF causes a good wettability by the matrix polymer. The PVDF obviously serves as composite mediator without which a separation of the other components might occur. 

Organic polymers, such as polyvinyhdene fluoride [PVDF (CH2CF2) ] and its copolymers with trifluoroethylene. 

Piezoelectric and ferroelectric polymers have been recognized as a new class of electroactive materials when the significant piezoelectricity in polyvinyhdene fluoride (PVDF or PVF2) was discovered by Kawai (1969). Since then, a variety of new piezoelectric polymers have been developed including copolymers of vinylidene fluoride and trifluoroethylene, P(VF2-TrFE), odd-numbered nylons, composite polymers, etc. These materials offer options of material selections for sensor and actuator technologies that need lightweight electroactive materials. 

In semicrystalline dipole electrets, polar crystallites are present in addition to the polar amorphous phase (Fig. 2b). In die technically most interesting semicrystalline dipole electrets such as polyvinyhdene fluoride (PVDF) and its copolymers with trifluoro ethylene (P(VDF-TrFE)) (Lovinger 1983) or hexafluoropropylene (P(VDF-HFP)), odd Nylons 7 and 11, polyureas, polyureflianes (PU), and some liquid crystalline polymers, the crystallites are ferroelectric (Vasudevan et al. 1979 Hattori et al. 1996). The terpolymer poly(vinyhdene-fluoride-trifluoroethylene— chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) has been shown to have relaxor ferroelectric properties as the CTFE group destabilizes die long-range order of the ferroelectric phase (Xu et al. 2001). 

Y. Liao, R. Wang, M. Xian, C. Qiu, A.G. Fane, Fabrication of polyvinyhdene fluoride (PVDF) nanofiber membranes by electro-spinning for direct contact membrane distillation, Journal of Membrane Science, 425-426 (2013) 30-39. 

HEM, hollow-fiber membrane FSM, flat-sheet membrane M, molarity T, temperature V, Hquid velocity gi, gas velocity PP, polypropylene PVDF, polyvinyhdene fluoride FIFE, polytetrafluoroethylene PMP, poly(4-methyl-l-pentene). 

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