PTFE vs PEEK: Which Material Is Right for Your Application?

# PTFE vs PEEK: Which Material Is Right for Your Application?

In the world of high-performance engineering plastics, Polytetrafluoroethylene (PTFE) and Polyetheretherketone (PEEK) are two standout materials. Both are renowned for excellent chemical resistance and high-temperature performance, yet they differ significantly in mechanical properties, processing methods, and pricing. This article provides a systematic comparison across multiple dimensions to help buyers make informed decisions.

## Material Properties Comparison Table

| Property | PTFE | PEEK |
|———-|——|——|
| Chemical Name | Polytetrafluoroethylene | Polyetheretherketone |
| Molecular Structure | (-CF₂-CF₂-)ₙ | Aromatic semi-crystalline polymer |
| Density (g/cm³) | 2.14–2.20 | 1.30–1.32 |
| Crystallinity | 50–70% | 30–35% |
| Color | White/translucent | Beige/amber |
| Flammability | UL94 V-0 | UL94 V-0 |

## Performance Parameters Comparison

### Mechanical Properties

| Parameter | PTFE | PEEK |
|———–|——|——|
| Tensile Strength (MPa) | 20–35 | 90–100 |
| Flexural Strength (MPa) | 10–20 | 170–180 |
| Flexural Modulus (MPa) | 400–600 | 3,600–4,100 |
| Elongation at Break (%) | 200–400 | 30–50 |
| Hardness (Shore D) | 50–65 | 80–85 |
| Impact Strength (kJ/m²) | 15–25 | 80–100 |

PEEK overwhelmingly outperforms PTFE in mechanical strength. PTFE’s tensile strength is only 20–35 MPa, while PEEK reaches 90–100 MPa—over three times greater. The差距 is even more dramatic in flexural modulus: PEEK’s 3,600–4,100 MPa is nearly 8 times that of PTFE (400–600 MPa). This means PEEK has a decisive advantage in structural load-bearing applications.

PTFE’s only mechanical “highlight” is its elongation at break of 200–400%, exhibiting exceptional flexibility and ductility, making it suitable for applications requiring tight sealing conformity.

### Thermal Properties

| Parameter | PTFE | PEEK |
|———–|——|——|
| Continuous Service Temp (°C) | -200 ~ +260 | -60 ~ +250 |
| Melting Point (°C) | 327 | 343 |
| HDT (°C, 1.8MPa) | 55 | 152 |
| CLTE (10⁻⁵/°C) | 10–13 | 4.0–4.7 |
| Thermal Conductivity (W/m·K) | 0.25 | 0.25 |

PTFE’s upper continuous service temperature of 260°C is slightly higher than PEEK’s 250°C, and PTFE offers outstanding cryogenic performance (-200°C), making it irreplaceable in deep-cold applications. However, PEEK’s heat deflection temperature of 152°C far exceeds PTFE’s 55°C, meaning PEEK maintains superior dimensional stability under load at elevated temperatures.

### Chemical Resistance

| Media Type | PTFE | PEEK |
|————|——|——|
| Strong Acids (conc. H₂SO₄, aqua regia) | ✅ Excellent | ⚠️ Limited |
| Strong Bases | ✅ Excellent | ✅ Excellent |
| Organic Solvents | ✅ Excellent | ✅ Good |
| Halogens | ✅ Excellent | ⚠️ Limited |
| Steam/Hot Water | ✅ Excellent | ⚠️ Limited long-term |

PTFE, known as the “King of Plastics,” offers exceptional resistance to virtually all chemicals, including concentrated sulfuric acid, aqua regia, and liquid fluorine. PEEK’s chemical resistance is also excellent, but has limitations under specific conditions such as concentrated acids, halogens, and high-temperature steam.

### Friction and Wear

| Parameter | PTFE | PEEK |
|———–|——|——|
| Dynamic Friction Coefficient | 0.04–0.10 | 0.20–0.30 |
| Wear Rate (×10⁻⁶ mm³/N·m) | 200–500 | 1–5 |

PTFE has an extremely low friction coefficient (0.04–0.10), the lowest among known solid materials, but its wear resistance is relatively poor. PEEK has a higher friction coefficient but an exceptionally low wear rate—only 1/100 to 1/50 of PTFE’s. In tribological applications, PTFE suits low-load sealing scenarios, while PEEK is better for high-load bearings and gears.

## Application Scenarios Analysis

**Typical PTFE Applications:**
– Chemical piping seals, gaskets, linings
– Cable insulation (high-frequency/high-temperature)
– Medical catheters, artificial blood vessels
– Cryogenic sealing (liquid nitrogen, liquid hydrogen)
– Non-stick coatings
– Laboratory ware

**Typical PEEK Applications:**
– Aerospace structural components
– Automotive engine peripherals
– Semiconductor manufacturing fixtures
– Medical implants (spinal, dental)
– Food processing machinery parts
– High-pressure seals and bearings

## Cost-Effectiveness Assessment

| Item | PTFE | PEEK |
|——|——|——|
| Raw Material Price (USD/kg) | 7–20 | 100–280 |
| Processing Method | Compression/extrusion/turning | Injection/extrusion/machining |
| Processing Yield | Medium (cold-press sintering) | High (melt processing) |
| Material Utilization | Lower | Higher |
| Overall Part Cost Ratio | 1× | 5–15× |

PTFE raw material costs are only 1/10 to 1/15 of PEEK’s, offering significant cost advantages. However, PTFE cannot be melt-processed and relies on cold-press sintering, which limits processing precision and yield. PEEK can be injection-molded, making it suitable for high-volume precision manufacturing, and the long-term cost gap may narrow.

## Selection Recommendations

1. **Choose PTFE when**: Extreme chemical corrosion environments (concentrated acids, halogens), ultra-low temperature operations (below -200°C), low-load sealing requirements, budget-constrained anti-corrosion projects.

2. **Choose PEEK when**: High-load structural components, high-temperature/high-pressure sealing, precision dimensional requirements, medical implants, melt-processable mass production needed.

3. **Compromise Solutions**: For moderate load + chemical corrosion scenarios, consider PEEK with fillers (e.g., carbon fiber-reinforced PEEK) or PTFE composites (e.g., glass fiber-reinforced PTFE) to balance cost and performance.

**Bottom Line**: If chemical resistance is the top priority, PTFE has virtually no equal; if mechanical strength and dimensional stability matter more, PEEK is the smarter investment. The key to selection is identifying the core constraint of your application—there is no “better” material, only the “more appropriate” one.