Fluoropolimers coatings - PFA coatings
PerFluoroAlkoxy alkanes (PFA) is a fluoropolymer. It is produced by copolymerization of tetraefluoroethylene (C2F4) and perfluoroethers (CF2F3ORf). In terms of its properties, this polymer is similar to polytetrafluoroethylene (PTFE). The big difference is that the alkoxy substituents allow the polymer to be melt-processed.
PFA is melt-processable by conventional thermoplastic processing methods, including injection, transfer, blow, and compression molding and by extrusion.
It is a relatively soft thermoplastic with lower tensile strength and creep resistance than many other engineering plastics. It is chemically inert and has a low dielectric constant over a wide frequency range.
PFA is used when extended service is required in hostile environments involving chemical, thermal, and mechanical stress. PFA offers high melt strength, stability at high processing temperatures, excellent crack and stress resistance, a low coefficient of friction.
It has high resistance to creep and retention of properties after service at 260°C (500°F). PFA also meets FDA 21CFR.177.1550.
PFA has high transparency (with good transmittance of UltraViolet and visible wavelengths.) It has long term weatherability and excellent resistance to ozone, sunlight and weather.
Important applications are linings for pipe and chemical processing equipment, roll covers, and several wire and cable applications, including aircraft wire, plenum cable, fire alarm cable, and well logging cable.
PFA – Perfluoroalkoxy - TYPICAL PROPERTIES
| Property | Value | Units | Method |
| MECHANICAL PROPERTIES | |||
| Tensile Strength, 73°F | 4060 - 4500 28 to 31 |
psi MPa |
|
| Elongation, 73°F | 260 - 300 | % | |
| Flexural Strength, 73°F | No break at flexure | D 790 | |
| Impact Strength, Izod | No break | ||
| Compressive Stress at 1% deformation, | MPa | D 695 | |
| Yield Strength At 23 deg C |
1740 12 |
psi MPa |
|
| Density (as polymerized) | 2.12 to 2.17 | gm/cu.cm | |
| THERMAL PROPERTIES | |||
| Coefficient of Linear Expansion 20 to 100 deg C |
12 x 10-5 | K-1 | |
| Melting Point | 487 - 540 253 - 282 |
deg F deg 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 |
|
| Heat Distortion Temperature, 66 lb/sq.in (0.455 MPa) |
158 to 171 70 - 77 |
deg F deg C |
D 648 |
| Service Temperature | -418 to 403 -250 to 206 |
deg F deg C |
|
| Processing Temperature | 698 - 743 370 - 395 |
deg F deg C |
|
| ELECTRICAL PROPERTIES | |||
| Dielectric Strength, short time, 0.080” |
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 | ? | 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 | nD 25 | 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 | ||
| CO2 Permeability | 273 | Ng cm m-2 s-1 | |
| O2 Permeability | 637 | Ng cm m-2 s-1 | |
| N2 Permeability | 91 | Ng cm m-2 s-1 | |
