What is PTFE: Everything You Need to Know

PTFE, a short form of Polytetrafluoroethylene, which is commonly known as Teflon. It’s a semi-crystalline fluoropolymer and widely known for its outstanding benefits to numerous industries, such as non-stick coating for kitchen pots and pans, as well as high-tech exotic medical uses like surgical instruments, test equipment, and implants. It’s also used in the automotive, chemical, and electrical industries.

Over the years, PTFE has become the dominant fluoropolymer as it rakes in a lot of market growth every year and the increasing trend is bound to continue in the coming years.

To enlighten you more about Teflon PTFE and why PTFE products manufacturers are recognized more than other manufacturers, in this post, we will discuss everything you need to know about PTFE.

What is PTFE– Polytetrafluoroethylene

PTFE is a strong, resistant, waxy, nonflammable synthetic material made from tetrafluoroethylene polymerization. It is identified by its slick and slippery surface, as well as its high melting point and resistance to attack from almost all kinds of chemicals.

The chemical structure of a Teflon material is similar to that of Polyethylene (PE), with the exception that the hydrogen atoms are fully replaced by fluorine. However, it should be noted that PTFE and PE are prepared and used in completely different ways.

In the modular structure of PTFE, the size of the fluorine atom forms a uniform and continuous sheath. It surrounds the carbon bonds, making the PTFE material more resistant to chemicals and have better stability. Also, due to the uniformity of the fluorine sheath, the PTFE material becomes electrically inert.

PTFE was first discovered by Dr. Plunkett of DuPont in the year1938; however, it was known to be an “accidental” discovery. Following that, in 1947, Chemours trademarked PTFE as “TeflonTM” and made it commercially available. It was after this that the development of other fluoropolymers began.

Without a doubt, fluoropolymer is a type of plastic with a wide range of properties. However, the discovery of PTFE changed the whole ecosystem of fluoropolymers and boosted their advantages in several applications.

Properties of PTFE

All fluorocarbons, including PTFE, get their properties from the combined impact of carbon-fluorine bonds. A highlight of the properties of polytetrafluoroethylene is the strong bond that Teflon materials have and the only chemicals that can affect this strong bond are highly reactive metals, such as alkali metals.

Below are the main properties of Teflon that make it a valuable commercial material.

·         High resistance to chemicals

·         Strong resistance to high and low temperature

·         Strong electrical insulation power both in hot and wet environments

·         Highly resistant to light, UV rays, and weathering

·         Reduced friction coefficient

·         Low dielectric constant

·         Good anti-adhesion qualities

·         Flexibility

·         Highly resistant to fatigue under low stress

·         Availability of high-purity grades for food and medicine

·         Low water absorption

·         Non-stick characteristic

·         Biocompatibility, non-toxicity, and inertness

Advantages and Benefits of Using PTFE

PTFE is a highly-rated fluoropolymer, and in terms of resistance to chemical, temperature, and non-stick properties, it’s the best among all fluoropolymers. In addition, PTFE has the following advantages:

·         The best cost-to-performance ratio.

·         Has a continuous operating temperature of +260 degrees Celsius, which is the highest operating temperature of any fluoropolymer.

·         Highly resistant to almost all chemicals.

·         A low friction surface that even a gecko would slip if it climbs.

·         Very resistant to electricity – a perfect insulator.

·         When the right raw polymer grades are selected, PTFE parts have translucent colors.

Because of Teflon’s material properties, it can withstand even the harshest of environments, making it appropriate for a wide range of applications. It is perfect for use in the food and beverage industry, from cooking equipment to food coverings, temperature sensor casing, conveyor belt rollers, and non-stick surface covers.

It is also very advantageous in the chemical industry as it can be used to make several products, ranging from gaskets to chemical tanks, and vessel linings. These advantages also cut across to the medical industry in the manufacturing of internal and external healthcare equipment, like catheters, syringes, bio-containment vessels, and sutures. In the same vein, it appeals to several industries, including the electrical industry.

Processing of PTFE

Before discussing the processing of PTFE, let’s see the different forms they can come in. PTFE is normally in granular, dispersion, and fine powder forms.

PTFE granular is manufactured in a water-based suspension polymerization reaction. It is produced by suspension polymerization in an aqueous medium with little or no dispersion agent. The resulting granular material is then processed to form the desired shape through compression molding.

PTFE dispersion products are manufactured in the same way as granulars, but with the addition of dispersing agents. They can either be used for PTFE coatings or processed into a thin film through film casting.

PTFE fine powder, on the other hand, is prepared in an emulsion polymerization reaction, which results in white, small-sized particles. The fine powder obtained from this can be paste extruded into thin sections or used as additional elements in other plastic materials to boost their resistance to wear and friction.

Processing PTFE is difficult and expensive, and this is because of its rigid polymer chain structure. It has a high melting temperature and high-melt viscosity, which makes it difficult to process through the normal methods – injection molding and extrusion. Its processing techniques are more comparable to those of powder metallurgy than the normal plastics processing. The processing techniques include:

On special machines, pre-sintered powders can be processed via sintering, pressing, paste extrusion, hot stamping, and compression molding.

Continuous fabrication of PTFE into tubes, tapes, and wire installation is done using paste extrusion, in which PTFE is combined with a hydrocarbon prior to molding a preform. And before sintering the part, the hydrocarbon should be vaporized.

Dispersion includes coatings, pulverization, metal coatings, cast for thin films, impregnation, and fiber spinning.

Operating range is within -270 degrees Celsius to 260 degrees Celsius.

The PTFE material properties have a significant impact on the processing technique. And in some specific applications where the PTFE property is not suitable, other fluoropolymers will be required.

PTFE Compounds

PTFE compounds means the adding of fillers or other additives to improve virgin PTFE properties. With the inclusion of these, the mechanical properties of PTFE can be enhanced, thereby reducing creep and wear. The common fillers that are used in boosting PTFE properties are glass fibers, carbon, carbon fiber, graphite, bronze, molybdenum disulphide (MoS2), and PEEK.

Glass Fiber

Glass fibers reduce the low and high temperatures of PTFE materials. The added quantity can be up to 40%. It improves wear resistance, compression strength, chemical resistance, and creep resistance. PTFE compounds filled with glass perform very well in oxidizing environments.

Carbon

Carbon reduces PTFE’s creep, improves its toughness, and elevates its electrical & thermal conductivity. It provides a low friction coefficient in dry water, steam applications, and resistance to chemicals. This compound is most suitable for non-lubricated purposes, like piston rings in compressor cylinders. Carbon-filled compounds can be made to be more resistant to wear by mixing them with graphite. Up to 35% carbon can be added.

Carbon Fiber

Carbon fiber reduces creep, boosts hardness, and increases flex and compressive modulus. Unlike glass fibers, carbon fibers are resistant to hydrofluoric acid and have strong bases. The thermal expansion coefficient of carbon fiber PTFE compounds is lower and has a high thermal conductivity. This type of PTFE compound is perfect for shock absorbers, water pumps, and other vehicle components. Up to 30% carbon fibers can be added.

Graphite

Graphite-filled PTFE compound helps in improving wear resistance, decreases friction, and increases sliding properties against soft metals – chemical inertness. Also, it improves the temperature resistance in some way. Up to 25% graphite can be added to PTFE compounds.

Bronze

Bronze-filled PTFE compounds have a high thermal and electrical conductivity, making them ideal for use in applications where a part is subjected to load at high temperatures. They improve compression strength, wear resistance, high thermal conductivity, and resistance to abrasion. Up to 60% bronze can be added to PTFE compounds.

Molybdenum disulphide (MoS2)

PTFE compounds that are filled with molybdenum disulphide (MoS2) have increased hardness and resistance to wear. They also have increased sliding properties and decreased friction. Up to 5% molybdenum disulphide (MoS2) can be added to PTFE compounds.