PCTFE (Kel-F) vs PTFE (Teflon)
PCTFE (Kel-F) and PTFE (Teflon) are both fluoropolymers with outstanding chemical resistance, but they trade off differently. PCTFE has lower gas permeability, higher strength (~36 vs ~25 MPa), better dimensional stability, and machines cleanly — ideal for cryogenic seals and valve seats. PTFE has the lowest friction, higher temperature tolerance (~260 vs ~150 C), and unmatched non-stick behavior, but it creeps (cold-flows) under sustained load.
The verdict
Choose PCTFE/Kel-F for low gas permeability, higher strength, dimensional stability, and precision machined cryogenic seals and valve seats. Choose PTFE/Teflon when you need the lowest friction, highest temperature tolerance, and best non-stick chemical-resistant performance, and can tolerate its tendency to cold-flow.
Side-by-side data
| Property | PCTFE (Kel-F) | PTFE (Teflon) |
|---|---|---|
| Category | Engineering Plastic | Engineering Plastic |
| Density (g/cm³) | 2.13 | 2.17 |
| Tensile strength (MPa) | 36 | 25 |
| Yield strength (MPa) | 36 | 15 |
| Elongation (%) | 130 | 300 |
| Hardness | R80 | D55 |
| Max service temp (°C) | 150 | 260 |
| Machinability | ●●●●● | ●●●●● |
| Corrosion resistance | ●●●●● | ●●●●● |
| Relative cost | ●●●●● | ●●●●● |
| Thermal cond. (W/m·K) | 0.22 | 0.25 |
| Typically used for | Cryogenic seals & valve seats | Chemical-resistant, non-stick, low friction |
Which should you choose?
Choose PCTFE/Kel-F when…
- Low gas and moisture permeability are critical — PCTFE is among the best barrier fluoropolymers
- Higher strength is needed (~36 vs PTFE ~25 MPa)
- Dimensional stability under load matters — PCTFE resists cold-flow far better than PTFE
- Precision machined seals and valve seats are required (machinability 4.0)
- Cryogenic sealing is the application (its best-fit use)
- Strong chemical resistance (5/5) with rigidity is needed
Choose PTFE/Teflon when…
- Lowest possible friction and non-stick behavior are essential
- Higher temperature tolerance is needed (~260 C vs PCTFE ~150 C)
- Broadest chemical inertness across aggressive media is required
- Cost matters — PTFE (~3.5) is cheaper than PCTFE (~5.0)
- The part is a low-friction bearing, liner, or non-stick surface
- Some creep/cold-flow under load is acceptable in the design
Key differences that matter
- PCTFE has lower gas permeability, higher strength (~36 vs ~25 MPa), and far better dimensional stability than PTFE
- PTFE offers the lowest friction, highest temperature tolerance (~260 vs ~150 C), and best non-stick behavior
- PTFE cold-flows (creeps) under sustained load; PCTFE resists creep and holds dimensions better
- PCTFE machines cleanly to precise tolerances (4.0); PTFE is softer and harder to hold tight tolerances (3.0)
- Both are fully chemically resistant (5/5) fluoropolymers
- PCTFE suits cryogenic seals and valve seats; PTFE suits low-friction, non-stick, high-temperature parts
- PTFE is cheaper (~3.5 vs ~5.0); PCTFE is a specialty, higher-cost material
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Open the Material SelectorGet a Quote →Frequently asked questions
Why use PCTFE instead of PTFE for seals?
PCTFE has much higher strength, better dimensional stability, and resists cold-flow, so machined seals and valve seats hold precise tolerances under load — whereas PTFE tends to creep and deform over time. PCTFE also has very low gas permeability, important for sealing against leakage. For precision cryogenic seals, those traits make PCTFE the better fit.
Which handles higher temperature?
PTFE, by a wide margin — it serves to about 260 C versus PCTFE's ~150 C. PTFE's exceptional thermal and chemical stability is a defining strength. So for high-temperature non-stick or chemical-contact parts PTFE wins, while PCTFE is chosen where strength, low permeability, and dimensional stability matter more than peak temperature.
What does it mean that PTFE 'cold-flows'?
PTFE creeps, meaning it slowly deforms under sustained mechanical load even at room temperature, so clamped or pressurized PTFE parts can lose dimension and seal force over time. PCTFE resists this cold-flow far better, holding its shape under load. In high-stability sealing applications, PTFE's creep is a real design limitation that PCTFE avoids.
Are both equally chemical-resistant?
Both are rated 5/5 and are essentially inert to almost all chemicals, as fluoropolymers. PTFE is the benchmark for universal chemical inertness and the lowest friction. PCTFE is also broadly resistant but is chosen for its mechanical strength, low permeability, and machinability rather than for exceeding PTFE's already excellent chemical performance.
Property values are typical/nominal figures for early-stage guidance only and vary by temper, grade, supplier and heat treatment. Confirm critical specifications against a certified datasheet or with an mfgiq engineer before production.