Perfluoroalkoxy (PFA)
PFA (perfluoroalkoxy) is a sister polymer to FEP & ETFE and also a derivative of PTFE. It was developed to enhance the properties of FEP to open up new markets. However, each material has distinct characteristics that set them apart from one another:
- Chemical Structure: PFA, FEP, and ETFE are all fluoropolymers, meaning they are composed of carbon and fluorine atoms. However, they have different chemical structures:
– PFA is a copolymer of tetrafluoroethylene (TFE) and perfluoroalkoxy alkane (the perfluorinated version of polyethylene glycol).
– FEP is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP).
– ETFE is a copolymer of ethylene and tetrafluoroethylene.
- Melting Point: PFA typically has a higher melting point compared to FEP and ETFE. This higher melting point can be advantageous in certain processing techniques where higher temperatures are required.
- Temperature Range: PFA has a broad temperature operating range, usually from approximately -200°C to +260°C (-328°F to +500°F). It can withstand higher temperatures than FEP and similar temperatures to ETFE.
- Chemical Resistance: PFA generally offers the best overall chemical resistance among the three fluoropolymers. It is highly resistant to a wide range of aggressive chemicals, making it suitable for applications in chemically harsh environments.
- Mechanical Properties: ETFE is known for its exceptional mechanical strength and toughness. It is significantly stronger than both PFA and FEP, making it more resistant to physical stress and impact. However, PFA has also great mechanical strength in excess of FEP.
- PFA offers more than 10 times the Flex Life of FEP.
- Transparency: FEP and ETFE are known for their excellent optical clarity and high transparency, making them suitable for applications requiring good light transmission. PFA, on the other hand, is slightly less transparent.
- Electrical Properties: All three fluoropolymers—PFA, FEP, and ETFE—are excellent electrical insulators.
- Cost: PFA is generally the most expensive among the three fluoropolymers. It has superior chemical resistance and higher temperature capabilities, which contribute to its higher cost.
- Holscot can secure High Purity granules often only available for semi-conductor markets.
In summary, PFA, FEP, and ETFE are all high-performance fluoropolymers with unique properties. PFA stands out for its excellent chemical resistance and broad temperature range. FEP and ETFE have advantages in different areas, such as optical clarity and mechanical strength, respectively. Engineers and designers select the most suitable fluoropolymer based on the specific requirements of their applications, considering factors such as chemical compatibility, temperature range, mechanical stress, transparency, and cost.
Holscot can manufacture tubing (30mm to 450mm diameter) and film in PFA (wall thickness 0.1 to 2-3mm) using our in-house extrusion lines, we can etch this to make it better able to adhere to other substrates with our in-house etching service of either Sodium Ammonia or Sodium Naptholene. The PFA can be heat expanded so that it is able to shrink down on application by the end user. All our PFA HST (heat shrink tubing) is carefully packaged to ensure it does not return to its original size before fitting, but we recommend it is not stored for more than a few weeks / month. PFA is ideally suited to heat-exchangers where we can potentially utilise repro polymer to benefit the price and the environment.
Trade Names for FEP resins include DuPont Teflon™, Daikin Neoflon™, Dyneon Hostaflon™, Solvay Solexis Hyflon™.
Technical Data for PFA:
| Property | Value | Units | Method |
|---|---|---|---|
| Mechanical Properties | |||
| Tensile Strength, 23°C | 4060-4500 28-31 |
psi MPa |
|
| Elongation, 23°C | 260-300 | % | |
| Flexural Strength, 23°C | No break at flexure | D 790 | |
| Impact Strength, Izod | No break | ||
| Compressive Stress at 1% deformation, | MPa | D 695 | |
| Yield Strength At 23°C |
1740 12 |
psi MPa |
|
| Density | 2.12-2.17 | gm/cu.cm | |
| Thermal Properties | |||
| Coefficient of Linear Expansion 20-100°C | 12 x 10-5 | K-1 | |
| Melting Point | 253-282 | °C | |
| Thermal Conductivity | 1.450.209 | Btu/hr-.ft-deg F W/m/deg K |
ASTM C 177 |
| Specific Heat | 0.25 1.047 |
Btu/lb/deg F kJ/Kg/deg K |
|
| Service Temperature | -250-250 | °C | |
| Processing Temperature | 370-395 | °C | |
| Electrical Properties | |||
| Dielectric Strength, short time, 2mm | MV m-1 | ||
| Surface Arc-Resistance | >300 (does not track) | sec | D 495 |
| Volume Resistivity, dry, @ 50% RH | >1018 | ohm-cm | D 257 |
| Surface Resistivity, @ 100% RH | 1016 | ohm/sq. | |
| Dielectric Constant 1kHz to 1GHz | 2.06 | ε | D150-81 |
| Dielectric Strength | 78.8* | kV mm-1 | D149 |
| Dissipation Factor @ 60 Hz – 1 MHz | <0.0001 | D150-81 | |
| Other Properties | |||
| Refractive Index | 1.344 | nD25 | D 542 |
| Water Absorption | <0.1 | % | D570-81 |
| Flame Rating+ | VE-0 | UL-94 | |
| Limiting Oxygen Index | 95 | % Oxygen | D 2863 |
| Resistance to Weathering | Excellent | ||
| Specific Gravity | 2.12-2.17 | D792-66 (1979) | |
| Static coefficient of friction | 0.05-0.08 | ||
Why Holscot?
- Proven manufacture, knowledgeable project management experience and excellent customer service all come as part of the package when working with Holscot.
- If you buy from Holscot, you will be buying directly from the manufacturer, based in the UK, not an agent or intermediary.
- Access to Holscot proprietary in-house manufacturing techniques and expert engineers.
- Holscot is a world leader in providing Fluoropolymer solutions, with more than 50 years experience supplying customers worldwide
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