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.
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.
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.
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:
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.
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 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 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 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 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-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-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.
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.
PTFE compounds filled with PEEK, benefit from increased thermal resistance, sliding properties, and surface toughness. They have superior properties in dynamic applications. Up to 20% can be added to PTFE compounds.
In general, the effects of PTFE compounds filled with fillers or additives include:
Result in outstanding PTFE properties at low and high temperatures.
Increases the porosity of PTFE compounds, and thereafter affects electrical properties. Dielectric strength reduces, while the dielectric constant and dissipation factor increases.
The type of filler or additive used has a significant impact on the PTFE chemical properties. Oftentimes, the chemical properties of filled PTFE compounds have reduced quality when compared to those of unfilled resin.
The electrical and thermal conductivity of PTFE is also affected by fillers and additives.
As it has been made evident severally in this post, Teflon properties are numerous, which has made them applicable to several sectors. In the next couple of paragraphs, we will be discussing some polytetrafluoroethylene applications.
The insulation of wiring in aerospace, electronics, and computer applications, such as hookup wire and coaxial cables are the most common use of PTFE as it accounts for nearly half of the total production.
PTFE is very applicable to this sector because it has outstanding dielectric properties, particularly low group velocity dispersion, notably at high radio frequencies, which makes it a good insulator in connector assemblies and cables, as well as printed circuit boards used at microwave frequencies.
This, combined with its high melting temperature property, makes it an excellent high-performance replacement for the weaker, higher dispersion, and lower melting-point polyethylene usually utilized in low-cost applications.
Many automobiles use PTFE parts particularly in the air brake systems where over-braided hose constructions are required. It is also ideal for usage on the outside edge of air compressors and this is because PTFE can withstand extremely high temperatures. Teflon material also helps to prevent carbon particle deposits, making it useful in several automobile applications.
In the aerospace industry, major parts like the tubing hoses, hydraulic hoses, and gasoline hoses are all made of PTFE. Most times, they are braided with Kevlar for increased protection. PTFE is also popularly used in applications that require heat temperings, such as water, alcohol, oil, and gasoline. You will also find it in pneumatic and hydraulic systems that are frequently used in the aerospace industry.
Furthermore, in the aerospace sector, PTFE film is frequently used in the fabrication of carbon fiber composites and fiberglass composites. PTFE film is utilized as a barrier between the carbon or fiberglass portion being produced and the breather and bagging materials used to encapsulate the bonding. This film prevents non-production materials from adhering to the component being fabricated, which is usually sticky because of the carbon-graphite or fiberglass piles being pre-pregnant with bismaleimide resin.
PTFE is commonly utilized as the liner in hoses for transferring chemicals, expansion joints, and product interchange lines, especially in applications involving acids, alkalis, or other chemicals. It is also found in refrigeration systems and steam pipelines.
Teflon PTFE typically replaces corrugated, stainless steel hoses. And this is solely due to PTFE’s extreme non-reactivity and high-temperature rating. Its frictionless properties let highly viscous liquids flow more freely, and it can be used in applications like brake lines.
Anyone who has the slightest experience with cooking knows that food tends to adhere to pots, pans, and other similar surfaces.
Formerly, oils and sprays were used to eliminate all traces of food from the kitchen utensils, but since Teflon material properties were discovered to include non-sticking, it has been used in manufacturing kitchen utensils. The introduction of PTFE-treated kitchen utensils provided cooks with a new choice. PTFE-coated cookware creates a non-stick surface that allows food to slip right off easily.
Furthermore, PTFE can withstand high temperatures without losing its initial properties. They break down only at high temperatures higher than those that are expected in a food preparation setting. This feature of PTFE is very valuable in fast food restaurants or any other establishment where food must be prepared quickly. With this, pots and pans only need minimal washing for them to be used again.
Machine parts can be difficult to keep in good working conditions because they corrode and become unusable over time. In fact, even the passage of time alone is enough to cause any expensive machinery to deteriorate. But PTFE helps prevent this type of damage and extends the machine’s operational life.
The secret to this is in Teflon’s capability to lubricate. When the several moving elements of machines come in touch with one another, they tend to generate a lot of friction. If this is left unchecked, it can result in major damage over time. But Teflon helps to minimize the friction to some extent, which prevents wear and tear.
PTFE is perfect for making machine parts, like gears, bushings, joints, slide plates, pipe linings, bearings, O-rings, and saw blades because of its incredibly low friction quality. In the operation of these parts, there is bound to be a lot of sliding movement, but PTFE’s low friction and self-lubricating property reduce all possible bad effects, thereby extending the life of the machine.
PTFE products have been on the market for more than 30 years in both the domestic and foreign medical industries. As a matter of fact, PTFE products have become widely used in all fields of surgery, and it is the world’s leading material used in administering grafts.
Also, PTFE coatings are crucial because they provide over-braid sealing, strength, and simplicity when cleaning and purging medical systems.
All materials used in the medical industry are required to meet very high standards because to some extent, they have the power over life and death. However, PTFE does not just meet these standards, it surpasses them. PTFE’s chemical inertness makes it ideal for fabricating artificial body parts.
Just as PTFE applies to several sectors, it is also used in making several products. A few of them are discussed below.
PTFE bellows combine the high corrosion resistance and fantastic flexible capability of PTFE. They are commonly used in the chemical, food, and medical industry majorly as balancing elements between engineering parts. Also, they can be used in protecting equipment from vibration and piping loads.
The diverse geometries of the fold can be designed and fabricated in extremely flexible and pressure-resistant variants to provide higher flexibility or compressive strength. When manufacturing below, it is important that aspects like the number of runs, external and internal pressure, and all-closed/all-open lengths are considered.
PTFE is frequently used as the raw material for valve seats and inserts, which are crucial components in the valve industry. PTFE seats have a low friction coefficient against metals, chemical inertness, and are compatible with a wide range of media. Filled grades have more resistance to wear and are capable of withstanding seating loads of the higher class of valves.
PTFE ball valve seats are designed to have a full-size port design that doesn’t restrict the flow of fluids. They are very effective in preventing reverse flow, and they have a smooth surface, which provides tight sealing.
PTFE seals are designed to have a slippery surface, which makes them ideal for sealing in moving systems like mass spectrometer probes and valves.
PTFE seals are capable of withstanding aggressive environments, high pressures, and dry running that other materials and elastomers are not suitable for. This is mainly because of PTFE’s properties – low friction, chemical resistance, non-sticky, and temperature. Also, they have high strength and are resistant to tear and abrasion. They are usable in several industries, including food & beverage, aerospace, and pharmaceuticals.
Like most other O-rings, PTFE O-rings seal the mating surface where two parts come in contact. They are often used around hoses, pipes, and any other fluid-transporting tubes. They are capable of easily slipping over cylindrical passages because of their ring-shaped design. While most O-rings can resist at least some heat, PTFE O-rings have very high heat resistance. They can withstand as much temperature as 350 degrees Fahrenheit without losing their functionality.
PTFE O-rings also have a low friction coefficient, As a result, they will cause damage to hoses and pipelines, so it’s safe to use PTFE O-rings with them. Also, they can withstand low and medium pressure perfectly without leaking.
PTFE guide rings are designed to prevent metal parts from contacting one another, and they also absorb occurring shear forces. They are very resistant to all kinds of media, which makes them suitable for several applications, such as mineral oil-based hydraulic liquids, flame-resistant hydraulic liquids, and environment-friendly hydraulic liquids and water-oil emulsions.
PTFE guide rings have excellent gliding capabilities, excellent emergency running features, and high wear resistance. They also aid in the reduction of mechanical vibrations.
Insulators are most often made with PTFE due to its exceptional dielectric properties, particularly at high radar and microwave frequencies. PTFE insulators are capable of withstanding temperatures ranging from -180 degrees Celsius to +260 degrees Celsius. It’s a high-performance alternative to polyethylene, which happens to be weaker and has a lower melting point. In fact, a lot of other materials cannot withstand such levels of temperatures.
PTFE insulators have the lowest friction coefficient of any solid and are resistant to water; they are exceedingly weatherable and non-adhesive, making them the best electrical insulation device available on the market.
Though PTFE has a plethora of advantages, it also has a significant number of disadvantages that one should look out for:
PTFE is the best of all fluoropolymers. In fact, it made other fluoropolymer materials become more applicable, even though it’s an odd plastic because it shares both the characteristics of thermoplastics and thermosets. It’s a thermoplastic material, but once it’s molded, it can’t be recycled.
But this doesn’t stop it from being a great polymer as it has some outstanding properties that a lot of polymers lack, such as low friction coefficient, capability to withstand high and low temperatures, dielectric properties, resistance to chemicals, impact, and other characteristics. And all these have made Teflon PTFE highly applicable to numerous industries, including pharmaceuticals, aerospace, automobile, kitchen utensils, etc.
Bellows Mechanical Seal are a type of mechanical seal where the spring element is a bellows. They are a critical component in preventing fluid or gas
In the world of engineering and manufacturing, where precision and efficiency are paramount, the role of wear resistance plastic has evolved far beyond their conventional image.
PTFE is a versatile polymer with outstanding properties like chemical resistance, low friction coefficient (self-lubricating), non-stick nature, and excellent electrical insulation. However, it also has some