Polyetheretherketone (PEEK)

Polyetheretherketone (PEEK), a high-performance thermoplastic, is prized in aviation for its exceptional strength and thermal resistance.

Background and Evolution

PEEK was developed in the late 1970s by Imperial Chemical Industries (ICI), entering commercial use in the 1980s. Its aviation debut came with aircraft like the Boeing 767, replacing metals in engine and structural parts due to its robustness. It plays a key role in modern planes like the Airbus A350, valued for its durability under extreme conditions.

How Polyetheretherketone is Used

PEEK, a tough beige or black plastic, is molded into:

• Engine Components: Forms bushings and thrust washers near turbines, enduring heat and stress.
• Structural Parts: Shapes brackets and fittings in airframes, supporting loads.
• Electrical Insulation: Used in connectors and cable sleeves, resisting high temperatures.
• Interior Fittings: Constructs seat frames and panel supports, offering strength and stability.

Why Polyetheretherketone is Used

• High Strength: Delivers tensile strength (~90–110 MPa), rivaling some metals for structural roles.
• Thermal Resistance: Operates up to 250°C continuously, thriving in engine zones.
• Chemical Stability: Resists fuels, solvents, and abrasion, meets FAA flammability standards (e.g., FAR 25.853), ideal for harsh environments.

• Lightweight: At 1.32 g/cm³, cuts mass compared to steel, boosting efficiency.
• Fatigue Resistance: Endures cyclic stress, ensuring long-term reliability.

Technical Specifications

• Density: 1.32 g/cm³, lighter than PPS.
• Melting Point: ~343°C, robust for thermal demands.
• Hardness: 85–95 Rockwell R, durable and wear-resistant.
• Elongation: ~20–50%, balancing toughness and flexibility.

Comparison to Alternative Materials

• PPS: Cheaper and heat-resistant, but less strong and fatigue-tolerant.
• PTFE: Better friction and chemical resistance, but softer and less structural.
• Nylon: More flexible and cost-effective, but degrades in heat.
• Titanium: Stronger and heat-tolerant, but heavier (4.5 g/cm³) and costlier.

PEEK excels in strength and heat endurance.

Role in Modern Aviation

In aircraft like the Boeing 777 and Airbus A380, PEEK reinforces engine parts, airframe fittings, and insulators, thriving in demanding roles. It pairs with PPS for heat resistance and POM for precision, enhancing performance in models like the Airbus A350.

Environmental and Economic Considerations

• Production: Energy-intensive synthesis, with high raw material costs.
• Cost: Pricier than nylon, offset by superior longevity.

• Recycling: Reprocessable, though limited by aviation-grade additives.

Future Trends

Carbon-reinforced PEEK or 3D-printed variants could expand its structural use, though cost may limit it to premium applications.

Summary

PEEK’s strength, thermal resistance, and stability make it vital for aviation’s engine and structural components. From its 1980s debut, it has delivered durability in extreme conditions, securing a high-performance niche.