Metal, Rubber or Plastic: What is PTFE Made From?
A guide to PTFE, how it’s used in the manufacturing industry, and most importantly, what' it’s made from!
PTFE may sound mysterious, but in reality, it’s one of the most versatile and widely used materials in the manufacturing industry. As a major advancement in modern science & technology, this innovative substance is now widely used by every person and in every industry - globally.
And that’s exactly what makes PTFE so amazing! It’s a material found in almost everything you use - from non-stick frying pans to the seat belt clips in your cars, there’s a big chance that you’ve actually used something that contains PTFE today without even knowing it.
Armstrong Energy Products
But, what is PTFE made of? Is it metal, rubber or plastic? The quick answer is neither of the three. It isn't metal, it isn’t rubber, and it also isn’t exactly plastic. More specifically, PTFE is a thermoplastic polymer primarily characterised by a slippery surface, high melting point, and resistance to “attack” by almost all chemicals.
You may have other questions – for instance, is PTFE different from Teflon? What industries often use it? This article provides a comprehensive guide that will answer all your basic questions about PTFE, including how it’s made and its various applications. You’ll also find some helpful information about some examples of products that are made with PTFE.
We’ll start with the basics, then we’ll delve into the common applications of PTFE – you’ll be surprised to learn it’s a key component of products we use every single day.
What is PTFE?
Commonly known by the registered trademark Teflon®, PTFE stands for polytetrafluoroethylene. Other trademarked brand names include Fluon, Hostaflon, and Polyflon.
PTFE is a fluoropolymer based on carbon and fluorine - hence the “fluoro” element in the name. It is also a polymer, meaning its molecular structure consists of a repeating pattern of large and similar particles. In this case, the particles are the compound tetrafluoroethylene, with a chemical formula of C2F4.
It was first discovered in 1938 by American company DuPont. Today, Teflon’s patent belongs to The Chemours Company, a chemist company spin-off of DuPont. However, many other manufacturing and industrial companies have since been producing their own PTFE-based products.
PTFE is well known for its versatile set of characteristics, making it highly suitable for an enormous range of applications. With its lack of reactivity to most other chemicals, a considerably high melting point, stability in very low temperatures, resistance to corrosion, insulating properties, durability, and slick, non-stick surface, PTFE has a virtually unlimited range of uses.
Most commonly, however, PTFE is used as a coating for other materials. Common examples include the coating of machine parts, construction materials, medical equipment such as catheters, cooking utensils, wiring, laboratory equipment and fabrics.
Is PTFE a Metal?
PTFE is not a metal. One of the defining properties of metal is its electrical conductivity, whereas PTFE is insulative. Nor is it rubber, even though it may kind of seem like one. So, while it isn’t technically a plastic, PTFE is effectively considered one because of its properties.
Rubbers, like plastics, are also polymers but possess the defining property of elasticity. Rubbers can be deformed, but hey will bounce back to their original form unless they are completely broken. On the other hand, plastics are defined by their plasticity, which means their shape and form can easily be manipulated by heat or force. PTFE belongs in the latter category.
How is PTFE Made?
The production of PTFE can be summed up in two main stages:
the synthesising of TFE or tetrafluoroethylene, and
the polymerisation of the TFE to make it PTFE.
Remember, PTFE stands for polytetrafluoroethylene.
Here’s a basic, abbreviated version of the production process:
❏ This process starts with four key components: fluorspar, hydrofluoric acid, chloroform, and water. These ingredients, minus water, are synthesised into TFE using a process called pyrolysis.
❏ The three components are placed in a chemical reaction chamber and heated to temperatures high enough to alter their chemical composition.
❏ Once the TFE is created, it is cooled to prevent a reverse reaction and potentially explosive decomposition.
❏ It is then turned into liquid and mixed with clean water in the reaction chamber. Iron is used as a reaction catalyst. The polymerisation of TFE into PTFE will then begin, and solid grains of PTFE will be formed.
However, it is important to note that this is just a very basic rundown of the process of making PTFE. There are often other steps involved to control the form and properties of the final product, depending on the manufacturer. In fact, different manufacturers may have different production processes.
What Are the Types of PTFE?
PTFE can be filled with other materials to slightly alter its properties based on the needs of the application or product to be manufactured. Below we look at the three most common fillers of PTFE:
Carbon-filled PTFE
Filling PTFE with carbon generally makes it more robust than PTFE alone. Carbon-filled PTFE offers higher compressive strength, as well as general deformation, creep, and wear resistance. Because carbon itself is also conductive, filling PTFE with carbon also erases its insulative properties and makes it a better conductor for both heat and electricity.
Glass-filled PTFE
Glass-filled - particularly fibreglass - is the most common kind of filled PTFE. The effects are quite similar to carbon filling, as glass also increases PTFE’s durability. Filling PTFE with glass similarly increases compressive strength and resistance to surface pressure and decreases flexibility. Glass also makes the PTFE more chemically resistant. It also maintains or even improves upon PTFE’s insulating properties.
However, the downside is that glass-filled PTFE generally has a significantly more abrasive surface, effectively removing pure PTFE’s smooth, slick surface. Glass filling also doesn’t increase the conductivity of PTFE the way carbon does.
Copper-filled PTFE
Copper or bronze-filled PTFE is also more durable than virgin PTFE, although not to the extent of carbon- or glass-filled PTFE. But what copper or bronze filling mainly does is to drastically increase the material’s conductivity - to the extent that it’s more of a conductor than an insulator. In fact, bronze-filled PTFE can be up to 10 times more conductive than unfilled PTFE. It also has more friction resistance than that of other fillings.
Copper-filled PTFE is, however, more chemically reactive and is thus more vulnerable to corrosion than your regular PTFE or glass- or carbon-filled PTFE. This is mainly due to bronze being easily oxidised.
It’s important to note that manufacturers often offer varying amounts of filling in their PTFE products to meet the client’s needs. It’s also not uncommon for manufacturers to fill PTFE with different mixed ratios of these fillers, aiming to balance their effects and achieve the ideal mix of properties.
What Are The Properties of PTFE?
PTFE can be used in numerous applications thanks to its many desirable properties as a manufacturing material. In fact, it’s so widely used that PTFE is a staple part of common construction projects – including bridges, car parks, supermarkets, schools, etc.
Let’s first take a look at its properties and limitations below.
Properties & Advantages of PTFE
❏ Non-wetting characteristics
❏ Does not embrittle or age
❏ Medical, industrial and food-grade material
❏ Low water absorption
❏ Low coefficient of friction and low dielectric constant/dissipation factor
❏ Good fatigue resistance when under low stress
❏ Resistant to strong, corrosive chemicals
❏ Resistant to high heat and low temperatures
❏ Resistant to light and UV
❏ Resistant to weathering
❏ Highly flexible
❏ Smooth surface finish achievable after fabrication
Limitations of PTFE
❏ Compared with other polymer materials, it is not low-priced
❏ Not easy to mass-produce
❏ Cannot be cemented or welded
❏ Can be difficult to join
❏ If under enough pressure, it can change its shape
❏ While it can withstand very high temperatures, it melts at 326˚C
❏ Low resistance to radiation
❏ Abrasion and creep sensitive
What Industries Is PTFE Used In?
Here are some common industries and applications where PTFE is used.
Industrial Manufacturing
PTFE’s durability means it holds its ground in the harsh environment of industrial manufacturing facilities. The material is used in a considerable portion of the components and equipment in many factories, including:
Industrial coating
Due to the aforementioned ability to withstand extreme temperatures and harsh chemicals, PTFE is most commonly used as a protective coating or covering.
It usually comes in either liquid or powder form that is then used to coat various products in a wide range of industries such as:
❏ Seat belt clips
❏ Non-stick scissors
❏ Non-stick frying pans
❏ Hose liners
❏ Aerospace engine components
❏ Medical catheters
PTFE is also involved in the manufacturing process of many products. For example, it can be used as a coating on tanks, pumps, pipes in chemical processing facilities, or in factories that produce fragile and sensitive products such as computer microchips.
PTFE industrial coatings are also applied in the electronics industries. A classic example is the coating for electrical wires and cables, drawing on its excellent dielectric properties. This includes:
❏ Hook-up wires inside computers
❏ Microwaves ovens
❏ Vehicle electrical systems
They are also used to coat coaxial cables used by internet and telephone service providers for data provision.
Not only is PTFE found in these finished devices, but it’s also frequently utilised in manufacturing them. As mentioned, the manufacturing of semiconductors, such as computer microchips, can get quite tricky due to the product’s fragile nature. This is where PTFE can be used to protect these microchips, making the most of its high resistance to chemical reactions.
PTFE films
PTFE can also come in transparent sheets or films that can be formed or shaped in many ways. They can be thermoformed, vacuumed formed, metalised, or even laminated to suit different needs and applications.
Such applications include:
❏ Erasable anti-graffiti surface coverings
❏ Sterile packaging
❏ Circuitry
❏ Anti-corrosion liners
❏ Pharmaceutical cap liners
❏ Radiometry equipment
❏ Adhesives
PTFE resins
PTFE can also come in powdered resin form. This form of PTFE is often used to make tapes and membranes, and sometimes even whole tubes.
These are then used to make, for example, hydrophobic yet breathable membranes, like those used in aerospace equipment. Membranes made from PTFE are also utilised in surgically treating glaucoma.
However, this versatile material can also be used to make cables, wires, and liners. PTFE resin is also particularly moldable and can be shaped to make various components such as gaskets, valves, seals, expansion joints, and bearing pads.
PTFE fabric
PTFE can also come in fabric form, which is used in construction as part of lightweight architecture. Often, PTFE fabrics have fibreglass woven into them.
Similarly, PTFE can also be used as a textile finish or repellent to protect clothes and other fabrics.
Chemical, Medical & Pharmaceutical Industries
Because of PTFE’s excellent chemical resistance, it will not corrode or react with most chemicals, making it a handy material to use in chemical, medical and pharmaceutical settings.
PTFE is often used in chemical facilities to make tanks and containers, line pipes and tubes, and other chemical-handling equipment. This is also intended to maintain the chemicals’ purity as the PTFE will not interact with them.
Other common examples of PTFE’s usage in the chemical industry include the following:
❏ Coating for magnetic stirrers
❏ Pumps
❏ Reaction vessels
❏ Autoclaves
❏ Impellers
❏ Chemical containers
❏ Heat exchanger coating
❏ Diaphragms
❏ Tubing for highly corrosive chemicals which will normally dissolve glass containers (i.e. hydrofluoric acid)
For similar reasons, PTFE also aids the medical and pharmaceutical industry due to its durability and chemical immunity. PTFE is also easy to clean and sterilise, making it conducive for medical environments and any other settings where contamination must be avoided.
Thus, PTFE is common in components of medical and pharmaceutical equipment such as valves, regulators and pressure control for equipment in these medical specialties:
❏ Dentistry
❏ Cardiopulmonary
❏ Respiratory
❏ Surgery
❏ Pediatrics
❏ Anesthesia
❏ Dental
❏ Surgical
❏ Emergency care
❏ Home care
Specific equipment examples include:
❏ Mini-Vacutron Unit made by Allied Healthcare Products, Inc. commonly used by healthcare facilities for post-surgery convalescence
❏ Oxygen separators used in medical equipment for patients with breathing problems
Related Questions
Is PTFE safe?
There have been concerns raised in the past about the safety of PTFE, mainly when used in cooking materials such as non-stick pans. The issue centred around the chemical PFOA or perfluorooctanoic acid, which was used in the making of Teflon-coated cooking equipment.
However, it is important to note that most (if not all) of the PFOA used in making PTFE-coated products is gone after the manufacturing process is complete. But, more importantly, Teflon-coated cooking equipment has been PFOA-free since 2013, when health associations raised concerns. As long as PTFE-coated frying pans aren’t heated over 300 degrees Celsius, they won’t break down enough to cause health hazards or safety issues.
What is the compressive strength of bronze-filled PTFE?
Compressive strength (or compression strength) refers to a material's capacity to withstand loads that tend to reduce in size. It is the opposite of tensile strength. Adding Bronze to PTFE provides better dimensional stability and a higher compressive strength of 10.5 MPa at 1% deformation.
Who invented PTFE?
PTFE was accidentally discovered in 1938 by Roy J. Plunkett while working for DuPont. He was trying to invent a better based cooling gas than what was available at the time. He was using chlorofluorocarbon and left it overnight. When he returned, what he discovered instead was PTFE.