Поли (винилиденфторид)

Химические свойства

Polyvinylidene fluoride (PVDF) is one of the most rigid and abrasion resistant of the melt-processible fluoropolymers. It has good chemical resistance, though hot sulfuric acid and hot amines can attack it. Like most fluoropolymers, PVDF is inherently flame retardant. It retains useful mechanical properties until 300 degrees F (149 degrees C).

Использование

Coatings, film, filter cloth, instrument linings, filtration membranes, pump parts and linings and valves.

Определение

ChEBI: A polymer composed of repeating 1,1-difluoroethyl units.

Методы производства

PVDF, the addition polymer of 1,1,difluoroethene, is prepared by high-pressure free-radical polymerization in aqueous systems. It has applications in electric and electronic devices, as weather-resistant binders for exterior architectural finishes, and in a number of areas of the chemicalprocessing industry. The lack of additives and thus the exceedingly low contamination levels make the polymer useful in ultrapure water systems, for example, where high purity is necessary for construction materials.

Общее описание

Poly(vinylidene fluoride) PVDF is a semi crystalline non-centrosymmetric polymer which exhibits piezo-, pyro- and ferroelectric properties. It is a linear polymer that shows permanent electric dipoles perpendicular to the direction of the molecular chain. These dipoles result from the difference in electronegativity between the atoms of hydrogen and fluorine with respect to carbon. Depending on the processing conditions, PVDF exhibits several different crystalline phases (α,β,γ,δ). The β phase of PVDF is the phase that exhibits the best ferroelectric and piezoelectric properties.

Промышленное использование

The properties are generally similar to those ofthe other fluorinated resins: relative inertness,low dielectric constant, and thermal stability(up to about 150°C). The resins (PVF2 resins)are, however, stronger and less susceptible tocreep and abrasion than TFE and CTFE resins.
Applications of polyvinylidene fluoride aremainly as electrical insulation, piping, processequipment, and as a protective coating in theform of a liquid dispersion.