Polyvinylidene Difluoride (PVDF)

Properties and Applications

Polyvinylidene difluoride (PVDF), also called polyvinylidene fluoride, is a highly inert specialty thermoplastic with a melting point of approximately 175°C. It is produced by free radical polymerization of 1,1-difluoroethylene (CH₂=CF₂).

The high head-to-tail structure in its polymer backbone results in high crystallinity, high melting temperature, and better mechanical properties at elevated temperatures. Like most other fluoropolymers, it has good thermal and oxidative stability, as well as outstanding weatherability but has substantially greater strength, wear and creep resistance than PTFE. It is also easier to process. However, its chemical resistance is not as good as that of PTFE. For example, it is attacked by strong bases, amines, esters, and ketones.

Polyvinylidene fluoride undergoes crosslinking when exposed to ionizing radiation which allows for the modification of its mechanical and thermophysical properties. Furthermore, it is (partially) compatible with a number of other resins including acrylics and methacrylics and acrylic rubbers (ACM).

PVDF resins can be processed and converted into many finished and semi-finished goods like films, rods, tubes, and sheets by common processing methods such as injection molding, extrusion, melt and solution casting and film casting.

PVDF is used in the aircraft, electronics, architectural coating and chemical industry. Important applications include chemical resistant valves, bearings, pump parts, and heat-shrinkable tubing. It is also used in the specialty packaging industry for agricultural and industrial films and for certain food packaging. Because of its higher cost, PVDC is often combined with other cheaper plastics or it is applied as a thin coating or laminate, for example to improve the chemcial resistance and weatherability of metals such as aluminum, and galvanized steel.

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