Choosing the wrong engineering plastic can mean premature seal failure, costly downtime, contamination incidents, or regulatory non-compliance. PTFE, PEEK, and Nylon are three of the most widely used high-performance plastics in industrial applications — but they are not interchangeable. Each has a distinct performance profile, cost structure, and ideal application range.
This guide provides a direct, property-by-property comparison to help design engineers, procurement managers, and maintenance teams make the right material selection decision.
At a Glance: The Three Materials
PTFE (Polytetrafluoroethylene)
The champion of chemical resistance and low friction. Best choice when aggressive chemicals, extreme temperatures, or zero lubrication conditions are involved. Widest service temperature range of the three.
PEEK (Polyether Ether Ketone)
The strength champion. Best mechanical strength and stiffness of the three, excellent at high temperatures, and FDA-compliant. Premium cost but unmatched structural performance.
Nylon (Polyamide / PA)
The economical workhorse. Excellent toughness, good wear resistance, easy to machine. Best choice for moderate-temperature, moderate-chemical-resistance applications where cost matters.
Property-by-Property Comparison
| Property | PTFE | PEEK | Nylon PA66 |
|---|---|---|---|
| Continuous Service Temp | −200°C to +260°C | −60°C to +250°C | −40°C to +120°C |
| Tensile Strength | 20–35 MPa | 100 MPa | 80 MPa |
| Coefficient of Friction | 0.04–0.10 | 0.35–0.45 | 0.25–0.35 |
| Compressive Strength | 12 MPa | 118 MPa | 90 MPa |
| Chemical Resistance | Excellent (all acids, bases, solvents) | Very Good | Fair (attacked by strong acids) |
| Water Absorption | <0.01% | 0.5% | 1.5–3% (hygroscopic) |
| Dielectric Strength | Excellent | Good | Good |
| Hardness (Shore D) | 55 | 85 | 80 |
| Density (g/cm³) | 2.15 | 1.32 | 1.14 |
| UV / Outdoor Resistance | Excellent | Good | Poor |
| FDA / Food Grade | Yes (virgin PTFE) | Yes | Some grades only |
| Relative Material Cost | Moderate | High (3–5× PTFE) | Low |
| Machinability | Excellent | Good | Good |
| Creep Resistance | Poor (cold flow) | Excellent | Moderate |
Chemical Resistance: PTFE Wins Clearly
For applications involving aggressive chemicals — concentrated acids, alkalis, oxidising agents, halogenated solvents, fuels — PTFE is the material of choice. It resists virtually all chemicals at service temperatures, with only a handful of exceptions (elemental fluorine, alkali metals in elemental form, and a few highly specialised fluorinated compounds).
PEEK offers good chemical resistance to most common industrial chemicals but can be attacked by strong sulphuric acid, glacial acetic acid, and some chlorinated solvents. Nylon is the weakest of the three — it swells significantly in water (due to moisture absorption) and is attacked by mineral acids and many solvents.
Verdict: PTFE for aggressive chemical environments. PEEK for moderate chemicals combined with high mechanical stress. Nylon only where chemical exposure is mild and dimensional stability in wet conditions is not critical.
Temperature Performance: A Near Tie at the Top
Both PTFE and PEEK handle temperatures up to approximately 250–260°C continuously. PTFE has the advantage at the low end, performing reliably down to −200°C (cryogenic conditions) while PEEK is limited to about −60°C. Nylon is the clear underperformer here, losing mechanical properties significantly above 100–120°C.
For cryogenic applications (liquefied gas handling, aerospace, lab equipment): PTFE is the only practical choice of the three.
For sustained high-temperature applications (sterilisation autoclaving at 134°C, high-pressure reactor internals): Both PTFE and PEEK qualify; choose based on other requirements.
Mechanical Strength: PEEK Dominates
If your application involves high structural loads — bolted flanges, bearing races, structural support elements, high-pressure valve seats — PEEK's tensile and compressive strength of ~100–118 MPa is far superior to PTFE's modest 20–35 MPa. PEEK also has excellent fatigue resistance and creep resistance, allowing it to maintain dimensions under sustained loading that would cause PTFE to cold-flow.
However, for many sealing applications (gaskets, valve packing, pipe flange seals), PTFE's lower modulus is actually beneficial — it conforms to surface irregularities and maintains a seal even on slightly imperfect flange faces, which stiff materials like PEEK cannot do.
Friction and Wear: PTFE is Uniquely Superior
No solid material has a lower coefficient of friction than PTFE. At 0.04–0.10, it outperforms PEEK (0.35–0.45) and Nylon (0.25–0.35) by an order of magnitude. This makes PTFE the standard material for:
- Bearing bushes and slideways requiring no lubrication
- Bridge bearing pads allowing thermal expansion movement
- Wear strips in packaging and conveyor machinery
- Piston seals in pneumatic cylinders
- Anti-friction liners in structural bearings
PEEK and Nylon can be used in bearing applications but require lubrication and have substantially higher wear rates.
Cost Considerations
Nylon is by far the most economical of the three — typically 5–10× cheaper than PTFE per kg and 15–25× cheaper than PEEK. However, material cost is only meaningful when the material actually meets the performance requirements. Specifying Nylon in a 200°C corrosive chemical environment to save material cost will result in rapid failure and far higher total costs.
Cost vs. Performance Rule of Thumb
Use the most economical material that meets ALL your requirements — not the cheapest material that meets SOME of them.
- Nylon where: temperatures <100°C, mild chemicals, no UV, cost-sensitive
- PTFE where: aggressive chemicals, low friction needed, wide temperature range, food/pharma compliance
- PEEK where: high mechanical strength + high temp + reasonable chemical resistance all required simultaneously
Application Decision Guide
| Application | Recommended Material | Reason |
|---|---|---|
| Chemical plant gaskets & seals | PTFE | Chemical resistance + conformability |
| High-pressure structural valve seats | PEEK | Compressive strength + temperature |
| Bridge bearing pads | PTFE | Ultra-low friction + long outdoor life |
| Gear bushings, cost-sensitive | Nylon | Adequate performance at low cost |
| Pharmaceutical vessel linings | PTFE | FDA compliance + chemical inertness |
| Downhole oil & gas seals | PEEK | High temp, high pressure, H₂S exposure |
| Food conveyor wear strips | PTFE | Non-stick + FDA + no lubrication needed |
| Electrical insulation (HV) | PTFE | Highest dielectric performance |
| Cryogenic seals (LNG, LOX) | PTFE | Only material functioning to −200°C |
| Structural aerospace components | PEEK | Strength-to-weight + temperature |
What About Other Alternatives?
The comparison doesn't end at PTFE, PEEK, and Nylon. Other materials worth considering in specific cases include:
- UHMWPE (Ultra-High Molecular Weight Polyethylene): Excellent impact resistance and low friction at low cost, but limited to ~80°C and poor chemical resistance to hydrocarbons.
- POM (Acetal/Delrin): High stiffness and good wear resistance, but attacked by acids and bases. Temperature limit ~100°C.
- PVDF (Polyvinylidene Fluoride): Better mechanical properties than PTFE with good chemical resistance, but limited to ~150°C and higher cost than PTFE.
- FEP / PFA: Melt-processable fluoropolymers with similar chemical resistance to PTFE but higher transparency and ability to be injection-moulded. Used for laboratory tubing and chemical vessel linings.
Frequently Asked Questions
Is PEEK better than PTFE?
It depends entirely on the application. PEEK is stronger, stiffer, and more creep-resistant than PTFE, making it superior for structural and high-load applications. But PTFE has far better chemical resistance, a lower coefficient of friction, and a wider temperature range (especially at cryogenic temperatures). They are complementary, not competing materials.
Can Nylon replace PTFE as a gasket material?
No, not in typical industrial sealing applications. Nylon absorbs moisture (causing dimensional changes), has poor resistance to acids and bases, and degrades above 120°C. PTFE gaskets will outlast Nylon gaskets by many multiples in chemical service and are the industry standard for corrosive environments.
Which plastic has the best chemical resistance?
PTFE has the best chemical resistance of any common engineering plastic. Of the three materials compared here, the ranking is PTFE > PEEK > Nylon by a significant margin. PTFE resists virtually all industrial chemicals at service temperatures.
Why is PEEK so much more expensive than PTFE?
PEEK is synthesised through a more complex and costly polymerisation process requiring specialized monomers. It is also produced in much lower global volumes than PTFE. The price premium (typically 3–5× PTFE) is justified only when PEEK's mechanical properties are genuinely required and cannot be met by filled-grade PTFE.
Need Help Selecting the Right Material?
Hindustan Nylons' engineering team can review your application conditions — temperature, chemicals, loads, dimensions — and recommend the optimal PTFE grade or form factor. We supply virgin, filled, and chemically modified PTFE across all standard and custom sizes.
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