PTFE for non-stick pans and PFA material for chemical labs. ...
PTFE for non-stick pans and PFA material for chemical labs. Both are strong carbon-fluorine polymers but are used differently.
Fluoropolymers come from the resins family as they contain fluorine and carbon bonds. Most people know Teflon at the domestic level, but several other types of fluoropolymers exist in the chemical industry.
They are highly resistant to acids, bases and many other solvents. Their unique features make them useful in various industries, from gas and oil to medical and automotive industries. Even in the aerospace and mineral industries big sectors also utilize these materials. The three materials that most industries use nowadays are PTFE, FEP and PFA.
PTFE is commonly used in non-stick cookware, and PFA is best for chemical labs for its resistance. Though both are carbon-fluorine polymers, their applications differ significantly. We are going to discuss the differences between these two widely used polymers. So, let's start.
What is PTFE?
PTFE is Polytetrafluoroethylene. It is a synthetic form of tetrafluoroethylene, which is used in various applications. It is a solid fluorocarbon due to its heavier molecule weight. This synthetic fluoropolymer doesn’t get wet due to its hydrophobic nature; it neither mixes with water nor water-containing materials.
Teflon, also sold as Syncolon or Fluon, is incredibly slippery thanks to the fluorine atoms in its makeup. These atoms carry a negative charge and are chemically unreactive, giving Teflon its signature low-friction surface.
The most interesting point about PTFE is its formation, which was accidental. On the 6th of April, 1938, it was discovered By Roy and his team when they were trying to make environmentally friendly coolants to use in domestic household refrigerators.
They were working on refrigeration gasses to make some safe, environmentally friendly, and non-flammable refrigerants. His team had the responsibility of monitoring a particular tetrafluoroethylene substance.
When they took out the sample from the freezer, they found that tetrafluoro ethylene substance became polymerized because of low temperature. Its color changes into a white solid with an appearance of wax texture. Everyone in their daily lives has been widely using this wax for more than the past 85 years.
●Hydrophobic
●Highly resistant to corrosive materials
●Low friction Coefficient
●Easy to machine
●Temperature strength
●Prevent wear and tear
●Insulator of electricity and heat
●non-stick frying pans and other cookware
●Lubrication of machines
●In the lining of tanks and substance-heavy containers
| Pros | Cons |
|---|---|
| Non-stick properties | Hard bulk manufacturing |
| Highest temperature resistance | Difficulty in processing |
| Opaqueness and Translucency | Requires unconventional techniques |
| Offers High-performance | |
| High chemical resistance | |
| High inertness | |
| Easy to install | |
| Lubrication | |
| Less expensive than other fluorocarbons |
PFA is similar to fluoropolymer plastic and a copolymer of perfluoro ethers and hexafluoropropylene. DuPont Co., the producer of PTFE, developed PFA, and their Teflon PFA is one of the most popularly recognized formulations.
PTFE has some disadvantages and copolymer fluorocarbon is created to cover them and to deal with its industrial limitations. PFA material is used in the making of several substances, which are quickly processed through various conventional techniques that are not possible with PTFE, from extrusion and welding to injection molding. PFA melts very quickly and changes into a liquid state, which is not possible in PTFE.
Teflon invented the PFA materials when they already used PTFE products with other fluoropolymers like FEP and PFA. History has no accounts related to its first creation story but told that different alkoxy groups were used in the process of making PFA. It's formed as a copolymer which is used to fulfill the limitations of PTFE, like extrusion. PFA has a higher meltable feature than PTFA, which is processed using conventional methods.
●Non-stick surfaces
●Low friction coefficient
●Wide temperature range
●Flexibility of polymer
●Highly resistant to stress cracking
●High thermal and electric resistance
●Highly resistant to corrosive solvents
●Chemical stability
●High dielectric strength
●Lab equipment
●Pipeline PFA tubing
●Sheet lining
●FRP replacement
●High grading applications
●Semiconductors
●Medical tubing
●Pumps
●Heat exchangers
●Valve liners
●Filtrations
●House fittings
●Pump housings
●Heat transfers
| Cons | |
|---|---|
| Highest temperature resistance in all fluoroplastics | Very expensive |
Effective substance processing through conventional techniques ●Molding |
Less Flex lifespan |
| Transparency | |
| Excellent chemical resistance | lower permeation |
| Highly resistant to extreme temperature | |
| Highly resistant to various environmental conditions | |
| Available in higher purity grades | |
| Bio-friendly alternative | |
| High-performance standards | |
| Cold flow resistance | |
| Excellent permeability |
As PFA and PTFE are fluoropolymers, they are best for their exceptional chemical resistance and high-temperature performance. They have many similarities, still they differ in several key properties, which we will discuss below. Depending upon these properties, both are suitable for different applications.
PFA is melt-processable through conventional techniques like injection molding and screw extrusion. This feature makes it best for creating complex shapes with cost-effective manufacturing in terms of fluoropolymers.
PTFE is not melt-processable by conventional and standard methods. It needs specialized techniques for creating shapes like compression molding or sintering.
PFA offers greater flexibility than PTFE. It is ideal for various applications requiring bending or complex tubing configurations like in the Chemical Delivery System. One example is medical tubing, where tight bends and intricate routing are required in some applications. PFA works efficiently for such tasks. PTFE has a longer flex life than PFA material, which makes it able to withstand more repetitive folding or flexing cycles.
PTFE has a higher thermal resistance. Its melting point is nearly 327°C which is higher than the melting point of PFA material of 260°C. This point makes PTFE offers better creep and flow resistance and thermal stability in extended service. PFA has thermal stability, which is beneficial in various applications requiring consistent dimensions over long periods.
When it comes to chemical resistance, both PFA and PTFE have somewhat the same resistance to most chemicals. They react with molten alkali metals and fluorine. PFA material absorbs moisture but in small amounts. PTFE strongly repels water as it is extremely hydrophobic.
It has a very low coefficient of friction than PFA, which makes it best for applications requiring non-stick surfaces or smooth movement.
In electrical properties, PFA and PTFE possess similar dielectric constants and dissipation factors but PFA material has a significantly 3-4 times higher dielectric strength than PTFE. This higher dielectric strength makes PFA material best for applications where electrical insulation is most crucial, especially under high voltage conditions.
When it comes to environmental resistance, PFA has superior salt spray resistance. It is slightly more prone to moisture absorption and specific weathering effects like UV degradation than PTFE. At high temperatures of up to 500°F, it maintains transparency while PTFE becomes milky white.
PTFE materials are more cost-effective because of their simpler processing requirements. PFA material is more expensive due to its melt-processability, but lower manufacturing costs for complex parts can offset this.
We have discussed some PFA and PTFE materials properties, but they are not fixed as they may vary depending on the manufacturer and grade with processing conditions. Sometimes, to meet the application requirements of some specific industry, manufacturers offer customization options, which also affect the features of the material.
PFA or PTFE are both important materials for use in various applications, like those that require flexibility and high purity with high-temperature use, PFA material is best to use. Such applications include
●flexible tubing
●chemical processing equipment
●electrical insulation
PTFE is best in applications that require high-temperature resistance with low friction and excellent chemical inertness. Such applications include
●gaskets, seals
●non-stick coatings
●wire insulation
After discussing the main difference between PTFE and PFA material, here is a quick comparison table for better understanding.
| PTFE | PFA | |
|---|---|---|
| Chemical Properties | Inert | Inert |
| Flammability | Non-flammable | Non-flammable |
| Tensile Strength | 25-35 MPa | 28-31 MPa |
| Dielectric Strength | 50-100 KV/mm | 55 KV/mm |
| Flexural Modulus | 345 - 620 MPa 50,000 - 90,000 PSI | 590 - 625 MPa 85,000 - 90,000 PSI |
| Density | 2.2 g/cm³ | 2.15 g/cm³ |
| Coefficient of Friction | 0.03-0.05 | 0.05-0.08 |
| Coefficient of Linear Thermal Expansion | 14 x 10-5/K | 12 x 10-5/K-1 |
| Electrical resistivity | >1018 OHM/CM | >1018 OHM/CM |
| Weathering Resistance | Excellent | Excellent |
| Elongation |
350-400% | 260-300% |
| Machinability | Excellent | Excellent |
| Radiation Resistance | Good | Good |
| Compressive Strength | 11-13 MPa | 12-15 MPa |
| Temperature Resistance | 260°C (500°F) | 260°C (500°F) |
| Specific gravity | 2.13 - 2.25 | 2.12 - 2.17 |
| Service Temperature (Melting Point) | 327°C (620.6°F) | 305 °C (581°F) |
| Use temperature range | -196°C to 260°C (-321°F to 500°F) | -200°C to +260°C (-328°F to +500°F) |
| Thermal Conductivity | 0.19 W/MK | 0.25 W/MK |
| MIT Folding Endurance | 1 x 106 | 1 x 105 |
| Cold Flow Resistance | >10% 6.9 MPa (1,000 PSI) 25 °C (73 °F) at 1,000 hrs |
>2% 6.9 MPa (1,000 PSI) 25 °C (73 °F) at 1,000 hrs |
| Hardness | 55–60 durometer | 55–57 durometer |
| Water Absorption | <0.01% | <0.03% |
| Cost | Relatively Cheap | Expensive |
Conclusion
PTFE and PFA material have many similarities and differences, but choosing one for your application depends on your application’s needs. PFA materials are best for flexibility and processability, but PTFE should be your choice to get thermal resistance and flex life with low friction. Don’t decide depending on the difference between PTFE and PFA materials; consult with a reputable fluoropolymer provider to get customized material according to your application’s needs.
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