PTFE (Polytetrafluoroethylene) and HDPE (High-Density Polyethylene) are both widely used polymers, but they differ significantly in mechanical and thermal properties. PTFE excels in high-temperature applications, with a maximum continuous service temperature of 260°C (500°F), far surpassing HDPE's limit of around 120°C. Mechanically, PTFE has lower tensile strength (1,500–3,000 psi) compared to HDPE's higher range (4,000–5,000 psi), but PTFE's low coefficient of friction (0.10) and superior wear resistance make it ideal for sliding or rotating parts. PTFE also boasts exceptional chemical resistance and near-zero water absorption (<0.01%), while HDPE offers better impact resistance and is more cost-effective for general-purpose applications. For extreme environments or custom ptfe parts, PTFE is often the material of choice, whereas HDPE is better suited for lower-temperature, high-impact scenarios.
Key Points Explained:
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Thermal Properties
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PTFE:
- Maximum continuous service temperature: 260°C (500°F) in air.
- Heat deflection temperature: 250°F (121°C) at 66 psi.
- Coefficient of linear thermal expansion: 8.9 x 10^-5 in/in/°F, indicating moderate dimensional stability under heat.
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HDPE:
- Maximum service temperature: ~120°C, making it unsuitable for high-heat applications.
- Lower thermal expansion than PTFE but less stable under prolonged heat exposure.
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PTFE:
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Mechanical Properties
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Tensile Strength:
- PTFE: 1,500–3,000 psi (lower, but sufficient for non-load-bearing parts).
- HDPE: 4,000–5,000 psi (higher, better for structural applications).
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Flexural Modulus:
- PTFE: 72,000 psi (more flexible under stress).
- HDPE: 150,000–200,000 psi (stiffer, less prone to deformation).
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Impact Resistance:
- PTFE: 3.5 ft-lbs/in (Izod), brittle compared to HDPE.
- HDPE: ~10 ft-lbs/in, better for high-impact environments.
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Tensile Strength:
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Friction and Wear
- PTFE has a dynamic coefficient of friction of 0.10, one of the lowest among polymers, ideal for bearings, seals, and custom ptfe parts.
- HDPE has higher friction but better abrasion resistance in low-wear scenarios.
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Chemical and Environmental Resistance
- PTFE: Near-zero water absorption (<0.01%) and inert to most chemicals.
- HDPE: Low water absorption but less resistant to strong oxidizers and solvents.
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Applications
- PTFE: High-temperature seals, electrical insulation, and low-friction components.
- HDPE: Pipes, containers, and outdoor products where cost and impact resistance are priorities.
For specialized needs like extreme temperatures or low friction, PTFE is unmatched, while HDPE offers practicality for everyday mechanical demands.
Summary Table:
| Property | PTFE (Polytetrafluoroethylene) | HDPE (High-Density Polyethylene) |
|---|---|---|
| Max Service Temp | 260°C (500°F) | ~120°C |
| Tensile Strength | 1,500–3,000 psi | 4,000–5,000 psi |
| Flexural Modulus | 72,000 psi | 150,000–200,000 psi |
| Friction (Dynamic) | 0.10 (Ultra-low) | Higher than PTFE |
| Impact Resistance | 3.5 ft-lbs/in (Izod) | ~10 ft-lbs/in |
| Water Absorption | <0.01% (Near-zero) | Low, but higher than PTFE |
| Key Applications | High-temp seals, bearings | Pipes, containers, outdoor use |
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