PTFE Vs. PFA: A Detailed Comparison Guide | DCW

PTFE VS PFA: A Brief Comparison Guide

Fluoropolymers originated from a family of resins characterized by the bonds between fluorine and carbon. Domestically identified as Teflon, several types of fluoropolymers are available in the chemical industry. They are essentially those carbon compounds having fluorine atoms. They are identified by their high-resistance properties towards acids, bases, and other solvents and are currently used in the automotive, oil, gas, medical, mineral, and aerospace industries. PTFE, FEP, and PFA are three of the most notable fluoropolymers used in these industries for their versatility.


While PTFE is extensively used in domestic frying pans for its non-stick properties, PFA is industrially an indispensable material for chemical labs due to its outstanding resistance. Although both belong to the same family of carbon-fluorine bonds, their applications are in contrast. The purpose of this article lies in clearly defining the two most-used polymers in the chemical-based industries, PFA and PTFE, and highlighting the key similarities and differences between them.

What Is PTFE?

PTFE parts
Source: Dechengwang

Expanded form: Polytetrafluoroethylene


Definition: Polytetrafluoroethylene is essentially a synthetic version of tetrafluoroethylene. Being a synthetic fluoropolymer, the molecule’s weight is heavier than others, making it a solid form of fluorocarbons. It does not mix with water or water-containing substances and doesn’t get wet. In other words, it is hydrophobic due to the loss of London dispersion forces. It has a low friction coefficient with solids attributable to fluorine’s negative charges and inertness. It is also referred to as Syncolon and Fluon but is mainly identified as Teflon.

History Of PTFE

It is interesting to know that PTFE was an accidental creation. Its discovery happened on the 6th of April, 1938, when Roy worked on certain refrigeration gasses. Their main aim was to make environmentally friendly, safe, and non-flammable refrigerants that can be used as coolants in the domestic household. His team was in charge of looking after a specific tetrafluoroethylene sample. When the sample was taken out of the freezer, he and his associates at the time found the tetrafluoroethylene sample to be polymerized due to low temperatures. It had turned into a white solid with wax texture, which has been used for more than 80 years in everyone’s daily life.

Properties Of PTFE

PTFE properties include:

 

  • Hydrophobic
  • Low friction Coefficient
  • High resistance toward corrosive materials
  • Ease of machining PTFE Teflon
  • Temperature strength
  • Preventer of wear and tear
  • Insulator of electricity and thermostatic environment

Applications Of PTFE

PTFE is used in the following applications:

 

  • Cookware: PTFE is known for its non-sticking and hydrophobic properties, which makes it a great contender for non-stick frying pans and a variety of other cookware. PTFE sealants are widely used for such properties.
  • Liner: PTFE is extremely non-reactive due to its inertness derived from Fluorine atoms. These non-reactive inert traits benefit industries where corrosive and reactive acids and bases travel through pipelines. They are also used in substance-heavy containers and tanks and help store reactive fluids.

Lubricants: The negative charges inherent in this fluorocarbon compound reduces its friction coefficient and make it slippery. Thus, PTFE enhances the smooth operation of machinery and reduces weathering away of parts and components. This fluorocarbon compound plays a significant role in optimizing the consumption of energy.

Advantages Of PTFE

PTFE is the most unique of all fluoro compounds ever to exist. It is widely referred to as the ancestor of fluoroplastics and is excellent for its differentiating characteristics. Its formidability lies in the following benefits:

 

  • Highest temperature resistance of about 260-degree celsius among all fluoroplastics
  • Translucency and opaqueness
  • High-performance capabilities in relation to its price
  • High inertness and chemical resistance
  • Non-stick properties
  • Ease in installation of PTFE O-rings
  • Lubrication
  • Relatively cheaper variety of PFAs and other fluorocarbons like FEPs

Disadvantages Of PTFE

PTFE’s primary disadvantages lie in the following:

 

  • Difficulty in processing 
  • Hard to manufacture in bulk 
  • Requires unconventional techniques for extruding and welding PTFE

What Is PFA?

PFA parts
Source: Dechengwang

Expanded form: Perfluoroalkoxy


Definition: PFA is another similar kind of fluoropolymer plastic. One can say that this copolymer fluorocarbon has been created to cover the disadvantages found in the popular PTFE. Thus, any substance made of PFA material can be quickly processed through conventional extrusion, welding, and injection molding techniques. This can be quickly melted and transferred in a liquid state, which was a significant industrial limitation in the case of PTFE. Similar to PTFE, they are characterized by a low degree of friction coefficient.

History Of PFA

PFA materials are invented under the name Teflon. Teflon is widely used for PTFE products but includes other fluoropolymers like PFA and FEP. PFA has been developed with different alkoxy substituents. Its history is unknown, but it originated as a copolymer that covers all the limitations of PTFE- such as the unconventional techniques for extrusion. It is a meltable version of PTFE that can be processed using conventional methods.

Properties Of PFA

PFA properties include:

 

  • Non-stick properties
  • Wide temperature range
  • Low friction coefficient
  • Flexibility of polymer
  • High-resistance to stress cracking
  • High resistance towards corrosive solvents
  • High thermal and electric resistance
  • High dielectric strength
  • Chemical stability

Applications Of PFA

PFA is widely used in the following applications:

 

  • Lab equipment: Due to its ample protection against chemical accidents, it is an extensively used material for plastic tools and equipment in chemistry labs as fluoropolymer labware supplies. Its transparency and flexibility are great contenders for testing and operations applications.
  • Tubing: PFA is also used for pipeline tubing where corrosive fluids flow. PFA has substantial abilities for handling corrosive acids and bases in chemical-based industries.
  • Sheet lining: It also acts as a safe lining replacement for tanks and containers
  • FRP replacement:  Carbon steel fiber reinforced plastics serve as alternatives for other alloys, which are much more expensive. PFAs play a significant role in initiating and facilitating the use of FRPs.
  • High grading applications: It is also ideal when the industry demands excellent purity and resistance to extreme temperatures and chemicals. They include medical tubing, semiconductors, pumps, valve liners, and heat exchangers. 
  • Other: Other applications include house fittings, filtrations, heat transfers, pump housings, and many more.

Advantages Of PFA

Perfluoralkoxy is highly regarded as a temperature-resistant version of other fluoroplastics like FEP. It has a lower melt processing viscosity than PTFE polymers and is characterized by the following advantages:

 

  • Highest temperature resistance of about 260-degree celsius among all fluoroplastics
  • Effectiveness of conventional PTFE molding, extruding, and welding techniques 
  • Excellent chemical resistance
  • High resistance to extreme temperatures and environmental conditions
  • Bio-friendly alternative
  • Availability of higher purity grades
  • Transparency
  • Sets performance standards in extreme chemical conditions
  • Excellent permeability due to less void density
  • Cold flow resistance (which facilitates deformation)

Disadvantages Of PFA

PFA’s primary disadvantage are as follows: 

 

  • Very expensive than alternative substances 
  • Flex lifespan is less compared to PTFE 
  • It retains lower permeation 

Common Grounds Of PFA And PTFE

Source: Dechengwang

PFA and PTFE, the two primary fluoroplastics used in chemical-based industries, are similar in several aspects as they come from the same family of fluorocarbons. The similarities are mentioned below:

 

Temperature range: PTFE and PFA have the same range of temperatures, which can be attributed to their high bonding strength between the atoms of fluorine, carbon, and oxygen. Both exhibit processability over 260 degrees Celsius (500 degrees Fahrenheit). 

 

Resistance to corrosivity: There are many instances in power plants where level measuring devices are constantly exposed to corrosive media. These aggressive fluids, like strong acids and bases, corrode these devices when they come in contact, especially with dense and viscous textures. The contacted components to such solvents can cause damage; the same is valid with tank lining. Custom PTFE and PFA manufacturers provide high resistance to such corrosion and can reduce the build-up of the product.

 

Hydrophobic properties: PTFE and PFA are both hydrophobic and will not get wet or contaminated when exposed to water-based solvents. This is extensively beneficial in areas where these solvents condense the antenna of the level-measuring device. When made with these fluorocarbons, the measurement will remain accurate and reduce the build-up.

 

Low friction coefficient: These fluoroplastics are characterized by a low friction coefficient, giving them a slippery and viscous texture. This property combined with the extraordinary PTFE temperature resistance, they are also used as lubricants.

 

Dielectric constant: The dielectric constants of fluoroplastics are the same, while the strengths may differ (PFA being superior by 3-4 times). Their dissipation factor is quite similar as well.

Differences Between PFA And PTFE

Source: Dechengwang
BasisPTFEPFA
Chemical PropertiesInertInert
Dielectric Strength50-100 KV/mm55 KV/mm
Tensile Strength25-35 MPa28-31 MPa
Coefficient of Friction0.03-0.050.05-0.08
Flexural Modulus495 MPa690 MPa
Coefficient of Linear Thermal Expansion14 x 10-5/K12 x 10-5/K-1
Elongation350-400%260-300%
Compressive Strength11-13 MPa12-15 MPa
MachinabilityExcellentExcellent
Service Temperature (Melting Point)-95 degree fahrenheit to -71 degree fahrenheit-95 degree fahrenheit to -71 degree fahrenheit
Thermal Conductivity0.19 W/MK0.25  W/MK
Cold Flow Resistance>10% 6.9 MPa>2% 6.9 MPa
MIT Folding Endurance1 x 1061 x 105
Water Absorption<0.01%<0.03%
CostRelatively CheapRelatively Expensive

From the above table, one can make the following inferences:

 

  • PFA is a superior alternative to PTFE on the grounds of flexibility, which can influence tubing applications. PFA’s capability to sustain multiple foldings (flex life) is comparatively lower than PTFE.
  • On the ground of resistance, PTFE takes advantage of thermal resistance. However, PFA is less hydrophobic than PTFE, which may not be feasible for level-measuring devices. PFA, as such, is much more prone to hydro-absorption and damage. 
  • PFA had superior salt spray resistance, high melting points, and service temperatures than PTFE, and its other copolymer, FEP. PFA’s melting point is 260 degrees celsius, while PTFE is 327 degrees. 
  • PFA has more potent electrical properties than PTFE. PFA’s dielectric strength is 3-4 times stronger than PTFE.
  • Alterations in alkoxy substituents make PFA a melt-processable version of PTFE, which makes it superior for ease in processing. 
  • PTFE is inferior on the ground of creep resistance, flow resistance, and temperature stability, while it excels in thermal resistance. 
  • PFA’s chemical resistance is on the higher end but is highly reactive to molten forms of alkali metals and fluorine atoms.
  • PFA is less cost-efficient than PTFE due to its ease of processing through injection molding.
  • It must be noted that most physical aspects vary by manufacturer, including length, diameter, size, brand, and grade. PFA and PTFE manufacturers are also open to customization possibilities.

Conclusion

The chemical industry is vast, and it is safe to say that fluoropolymers are responsible for several applications run in these sectors. These fluoropolymers are indispensable in many chemical industries and applications, thanks to their strong resistance to corrosive elements and non-solubility characteristics. PFA and PTFE are similar in their reactions toward electricity and non-flammable characteristics. Their surface resistivity, dissipation factor, and dielectric constants are virtually identical. 


The bottom line is that PTFE and PFA are superior in various aspects, whether electricity, service temperatures, cold flow, or multiple folding properties. Contact us to get a wide range of quality manufactured PTFE and PFA components for multiple industry specializations!

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