PVDF vs PTFE: What is the Difference

PTFE and PVDF are both high performance plastics, but there is still something different.Although they are all fluoropolymers, they differ in chemical structure, properties, manufacturing processes, and applications.Next, I will explain their specific differences to you.

Chemical Structure

PTFE is a perfluorinated polymer, polymerized from tetrafluoroethylene monomers.The chemical formula of PTFE is (C2Ф4)n One carbon atom is bonded to two fluorine atoms, which form a protective layer, giving PTFE its strong chemical inertness.

PVDF is a partially fluorinated polymer.It is polymerized from vinylidene fluoride monomers at temperatures ranging from 10 to 150°C. Its chemical formula is (C2ЧАС2Ф2)n

Характеристики

 

Performance	ПТФЭ	ПВДФ
Meliting Point	327℃ (620.6℉)	170~180℃ (338~356℉)
Continuous Temperature Range	-200~260℃ (-328~500℉)	-40~150℃ (-40~302℉)
Плотность	2.1~2.3g/cm3	1.75~1.78g/cm3
Предел прочности	15~30MPa	35~50MPa
Dielectric Constant	2.0~2.2	6.0~8.0
Теплопроводность	0.24~0.27W/(m⋅K)	0.12~0.17W/(m⋅K)

Химическая стойкость

PTFE is chemically stable, reacts almost no with any chemicals, and is resistant to corrosive liquids such as strong acids and alkalis. Its inertness comes from the carbon-fluorine bonds in its chemical formula.

PVDF’s chemical stability is slightly inferior to PTFE, but it’s still among the best in plastics. It’s resistant to acids, alkalis, and organic solvents, but not to certain strong oxidizing acids. However, PVDF has strong antioxidant properties.

Temperature Range

PTFE has a very wide temperature range, and it can work stably in environments ranging from -200 to 260°C (-328~500℉) without affecting its performance.If PTFE can maintain short-term operation for 2 hours at temperatures exceeding 260°C but below 300°C, this represents its peak temperature resistance.

PVDF has a slightly smaller temperature range than PTFE. Its continuous operating temperature range is -40 to 150°C (-40~302℉), and its peak temperature is 180°C, which can only be maintained for a short period of 1 hour. Therefore, PVDF is only suitable for some medium-level scenarios and cannot be used for a long time in extreme environments.

Механическая прочность

PTFE has low mechanical strength and is prone to deformation under high load conditions. Because it is a flexible plastic, it is not suitable for operation under high pressure.

PVDF has higher mechanical strength and extremely high fatigue and creep resistance. At the same time, PVDF also maintains structural integrity, making it more durable during operation and suitable for high-intensity, high-load conditions.

Тепловые свойства

PTFE has a high melting point of 327℃, making it suitable for many high-temperature environments.

PVDF has a melting point of 177℃, so it can only be used in medium and low temperature operating conditions.

Электроизоляция

PTFE has high resistance and a low dielectric constant, only 2.0 to 2.2, which means it can be used as an insulator, such as the insulation layer of wires and cables.

PVDF also has excellent insulation properties, and its dielectric constant ranges from 6 to 12, enabling it to store electrical energy and be used as a capacitor or electrical connector.

Radiation Resistance

PTFE has poor radiation resistance; in a high-radiation environment, its molecular chains will break, causing it to lose its mechanical properties.

PVDF has stronger radiation resistance, not only resisting ordinary ultraviolet radiation but also being able to withstand gamma rays. Even with prolonged exposure, the performance of PVDF degrades very slowly.

Transparency

PTFE is opaque and milky white. 

PVDF is transparent.During the processing, the internal structure and technological process can be observed.

Manufacturing Process

Because PTFE has a high melting point, it is more difficult to process, requiring extremely high temperatures to melt it. It must be shaped using specialized sintering techniques, which increases the cost of producing PTFE.The following are PTFE production processes under three different physical states.

• Dispersed

This form of PTFE is typically used to make films or coatings.

• Granular

Granular PTFE can also be understood as molded powder. It is generally made into seals, gaskets, pipe components, etc. by molding, and then sintered and cooled.

• Powder

This type of PTFE is in paste form and is produced using an extrusion process. It is generally used to manufacture tapes, tubes, and rods. In addition, it can also be used as an additive in other materials.

Compared to PTFE, PVDF has a simpler production process. It can be melt-processed, and whether it is extrusion molding or injection molding, it can produce high-quality products while also being cost-effective.The following is about the casting method of PVDF.

• Spin Coating

It is commonly used to make thin films.This fabrication method involves dropping a PVDF solution onto the center of a substrate, and then using centrifugal force to spread the solution evenly during the substrate’s high-speed rotation, thus forming a PVDF film.It is conceivable that films made in this way will be more uniform.

• Solution Casting

PVDF is added to a specific solvent, the mixture is poured into a mold, and then cooled to solidify. This process is generally used to produce porous polymer membranes.

• Melt Casting

The process involves melting granular PVDF, heating it to 225 to 235 degrees Celsius, pouring it into a mold, cooling it to 90 degrees Celsius, and then demolding it. However, this method can cause air bubbles.

• Thin Film Casting

This method is similar to solution casting, but it allows for more precise control over the thickness and uniformity of the thin film.

Приложения

Химическая промышленность

PTFE is commonly used to make reactor liners and acid tank liners. Because it can withstand strong acids and alkalis, it is ideal for use as a liner in the chemical industry.

PVDF is suitable for manufacturing halogen liquid pipelines. Due to its relatively weak chemical inertness, it can only be used in low to medium acid and alkaline corrosive environments.

Electronics Industry

PTFE is often used as insulation for wires and cables, and as a coating for electronic components or circuit boards.

PVDF can balance electrical performance and mechanical robustness, and is therefore often used as a connector coating or semiconductor device coating.

Аэрокосмическая промышленность

PTFE is suitable for lightweight seals in the aerospace industry. Due to its relatively low mechanical strength, it is suitable for static seals such as gaskets.

PVDF is widely used in aerospace applications, being manufactured into structural components. Due to its strong mechanical properties, it is suitable for dynamic sealing in pipes, pump assemblies, and other applications.

Medical Field

Both PTFE and PVDF are biocompatible, but their advantages can be applied in different areas. In the medical field, PTFE is used as artificial blood vessels, heart valve liners, and orthopedic prosthesis coatings. Because of its extremely low friction, it is less likely to cause damage from friction with human tissue, and it is resistant to corrosion from body fluids, making it suitable for long-term implantation.At the same time, it is also used to manufacture some consumable parts, such as the sealing ring for syringe pistons and sterile filter membranes.

PVDF is often used to manufacture high-end consumables, such as hemodialysis tubing and pharmaceutical storage bags. This is because its pore size allows for solute separation, it is resistant to corrosion from most pharmaceutical solutions, and it is relatively cheaper than PTFE.In addition, because PVDF is easy to process and can be directly injection molded into complex shapes, it is used to make surgical instrument handle shells, which also meets the rigidity requirements.

Environmental Protection and Sustainability

PTFE is difficult to degrade due to its chemical inertness and high-temperature resistance. Currently, it is mostly disposed of by incineration, but this easily produces harmful gases, and its actual recovery rate is less than 10%. The environmental burden caused by its degradation is far greater than that of PVDF.

PVDF is slightly easier to degrade than PTFE, and its pollutant emissions are 30-35% lower, with an actual recovery rate as high as 60-80%.

Neither PTFE nor PVDF are easily degraded in the natural environment, so engineers are currently researching efficient recycling methods to promote sustainable development.

Pros and Cons

PTFE is chemically inert, has a wide temperature range, and low friction.However, it is slightly expensive and cannot be melt-processed.

PVDF has high mechanical strength, is resistant to gamma rays, is transparent, and can be melt-processed.However, its operating temperature range is low.

Заключение

In summary, PTFE is suitable for applications requiring extremely high chemical stability and temperature resistance, while PVDF is suitable for applications requiring high cost control and mechanical strength.

If you need to order PTFE or PVDF products, please contact us. Hansa is a factory specializing in plastics manufacturing for 25 years, with rich experience and knowledge. We welcome your inquiries or orders.

Часто задаваемые вопросы

Is Teflon PVDF?

No, Teflon is another name for PTFE, which is a registered trademark of DuPont.

Is Teflon illegal now?

No, the FDA states that Teflon is completely safe for use in cooking and food processing and poses no harm to humans.

What is the alternative to PVDF?

There are many materials that can replace PVDF in certain aspects, but none can completely replace it. It depends on the specific functional requirements to determine which material best suits your needs. For example, in applications requiring high mechanical strength, PEEK can effectively replace PVDF.

What will replace PTFE?

Similar to PVDF, if you want to find a material that can replace PTFE, you need to look at it based on the specific application scenario, because each material has different advantages and properties.