Polyvinylidene Fluoride (PVDF)
Polyvinylidene Fluoride (PVDF) is a highly non-reactive thermoplastic fluoroppolymer.
-(CH2CH F)n-
“PVDF is a specialty plastic material in the fluoropolymer family; it is used generally in applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low smoke generation during a fire event. Compared to other fluoropolymers, it has an easier melt process because of its relatively low melting point of around 177 °C.”
“It has a low density (1.78) and low cost compared to the other fluoropolymers. It is available as piping products, sheet, tubing, films, plate and an insulator for premium wire. It can be injected, molded or welded and is commonly used in the chemical, semiconductor, medical and defense industries, as well as in lithium ion batteries.”
(Wikipedia, Polyvinylidene Fluoride (PVDF), 11/26/2010)
A polyvinylidene fluoride resin (PVDF) is a crystalline resin (50-60 % crystallinity) having a low glass transition temperature (-35 C) and is excellent in heat resistance, chemical resistance, mechanical properties (for example, tensile strength, flexural modulus, flexural strength, compressive strength and impact resistance), abrasion resistance, flame retardancy and weatherability. The PVDF resin also develops extremely specific electrical properties in cooperation with a feature that a dipole moment of a C--F bond in its molecular structure is high. When poled, PVDF is ferroelectric showing piezoelectric and pyroelectric properties.
The PVDF resin has a wide processable temperature range from its melting point to its decomposition point with good melt-flow. The PVDF resin is suitable for secondary processing such as machining, bending or welding after primary processing.
However, the PVDF resin has a drawback that a molten resin is colored when a molding temperature becomes high such as during njection molding or extrusion. In order to avoid the coloring of the molten resin, the molding temperature is generally 280.degree C or lower.
(Ikeda et al, US Patent 7,807,088, 10/5/2010)
Filled PVDF Materials
Fluorinated Polymers
PLA /PVDF Blend Scaffolds
Polymers /Resins
PVDF Blends
PVDF /Carbon Fiber Composites
PVDF Copolymers
PVDF/Fiber Composites
PVDF Fibers
PVDC Film
PVDF Proton Exchange Membranes
Recent US Patents
10/5/2010
7,807,088
Polyvinylidene fluoride resin powder for melt molding and process for producing molding from the resin powder
Ikeda et al of Kureha, Japan developed a PVDF powder suitable for injection molding or extrusion without pelletizing based on special particle size distribution which is high in bulk density (bulk specific gravity) and low in angle of repose, excellent in flowability and good in intermeshing with a screw installed in a cylinder of an injection molding machine or extruder. (RDC 12/20/2010)
Recent Journal Articles
Tailoring porous structure of ferroelectric poly(vinylidene fluoride-trifluoroethylene) by controlling solvent/polymer ratio and solvent evaporation rate
(2442-2450) European Polymer Journal 47 #12 (2011)
California et al, Portugal and Spain, produced ferroelectric macroporous poly(vinylidene fluoride-trifluoroethylene) membranes by isothermal crystallization from the solution at different temperatures starting from different diluted solutions of the co-polymer in dimethylformamide. In this way pore architecture, consisting in interconnected spherical pores can be obtained. It was also observed that the temperature or initial concentration of the crystallization process does not affect the phase, ferroelectric transition temperature or the melting temperature of the polymer. (RDC 11/16/2011)
Effect of electric field on the structure and piezoelectric properties of poly(vinylidene fluoride) studied by density functional theory
(3575-3581) Polymer 51 #15 (2010)
Wang, Fan and Ye of Northwester Technical University, China studied the geometry and piezoelectric properties of chain in PVDF under different electric fields by the density functional theory (DFT). The simulation gives optimized geometry of PVDF of α chain and β chain, with rotation angle around ±50° and arbitrary angle between 175° and 185° respectively. The energy barrier is about 16.16 kJ/mol in the chain transition from α chain to β chain, and the one of reverse transition is about 6.24 kJ/mol. It is found that the change of geometry increases dipole moment and the change of electronic properties decrease dipole moment under positive electric field and the geometry plays an important role. (RDC 12/22/2010)