Sheet in PVDF 1000x500 mm black

PVDF, polyvinylidene fluoride, is a semi-crystalline fluoropolymer chosen for its combination of chemical resistance, high temperature range and good mechanical properties. The sheet format is used where a fully strong, dimensionally stable surface is needed in a process environment, often as a tank wall, lining, slide rail or machining stock for parts that have to handle aggressive media. Compared to PTFE, PVDF is stiffer and harder, which makes it more suitable when the construction has to carry a mechanical load and not just deal with the chemicals.

The material handles continuous service up to about 150 °C and works down toward −20 °C. The density is about 1.78 g/cm³, which is high for an engineering plastic and a result of the fluorine content. The flame rating is V0 per UL 94, and water absorption is very low, around 0.04 percent. That means the sheet keeps its dimensions even during long exposure in damp or wet processes and does not change character over time from moisture uptake. The coefficient of thermal expansion is roughly 0.12 to 0.14 mm per meter and degree, which needs to be taken into account in constructions with wide temperature spans or long straight runs.

The chemical resistance is broad. PVDF handles most acids, oxidizers, aliphatic and aromatic hydrocarbons, chlorinated solvents and halogens at room temperature and at elevated temperatures. The material is not resistant to strongly alkaline environments at high temperatures, to certain polar aprotic solvents such as acetone or DMF, or to fuming sulfuric acid. When selecting against a specific medium the temperature is decisive, and a datasheet check against the exact concentration and operating temperature is always worth the trouble. For processes containing chlorine, bromine and fluorine, PVDF is one of the few engineering plastics that manages long-term service without the material breaking down.

Mechanically, PVDF is stiff and tough for a fluoropolymer. It has good impact and abrasion resistance, keeps its stiffness well up into the temperature range and has good creep strength under moderate loads. Friction is low, the surface is smooth, and the material shows good UV resistance in outdoor exposure, which is unusual among engineering plastics and one of the reasons PVDF is used in roof and facade laminates and in process equipment mounted outdoors. The material also has good electrical insulation and piezoelectric properties in certain variants, but in sheet format the latter are rarely used in classic process industry.

Machining is done with sharp carbide tooling. Sawing, milling, turning and drilling work well with the right cutting geometry and a moderate feed to keep heat build-up down, since thermal conduction is low. The sheets can be welded with the hot gas method or extrusion welding and thermoformed with a relatively narrow process window. Bonding is harder than for many other plastics and usually requires surface activation, either mechanically or with plasma, for the adhesion to work. For larger tank constructions, extrusion welding is standard, and corners and flanges are often made with prefabricated parts that are then welded in place.

Typical applications are tank linings and tank walls in acidic or halogen-bearing chemical environments, process tubes and flanges, valve components, gasket supports, semiconductor and process parts where cleanliness and chemical stability are required, and equipment for exhaust gas cleaning and electrolytic applications. The material also appears as wear and slide rails in equipment handling aggressive media and as machining stock for parts in pharmaceutical production. PVDF is further used as a surface lining against concrete in industrial floors where the combination of chemical resistance and wear strength is needed.

When choosing thickness, the load and the way the construction is built decide. For linings and panels with close support behind them, 2 to 8 mm is often enough. Free-standing walls and tank bottoms as a rule need 10 to 25 mm, and machining stock for parts is sized to suit the finished detail. The material is handled as a technical construction material; design for thermal expansion and plan for welded joints with room to move in applications with wide temperature spans.

In contact with pure water systems and ultrapure water, PVDF is one of the few plastic materials that manages long-term service without giving off leachable components in any significant amount, which is one of the reasons the material shows up in semiconductor and pharmaceutical production. At mechanical connections to metal, the difference in thermal expansion is something to take into account; flexible gaskets and oversize holes for flange bolts usually solve it.

Do you want to discuss a specific chemical medium or compare PVDF against PTFE and ECTFE for your case? Get in touch and we will go through resistance, temperature and price together.

The same handy 1000x500 mm but in black, a common choice where light coming in is not wanted in the process vessel.