PEEK Plastic: Properties, Applications, and Maintenance

Introduction to PEEK

Polyether Ether Ketone (PEEK) is a High-performance thermoplastic polymer belonging to the polyaryletherketone (PAEK) family. Renowned for its exceptional mechanical, thermal, and chemical resistance properties, PEEK has become a material of choice in demanding engineering applications. With a continuous service temperature of 260°C (500°F) and short-term exposure capability up to 300°C (572°F), PEEK maintains structural integrity where most polymers fail.

Material Properties

The exceptional performance of PEEK stems from its semi-crystalline structure and aromatic molecular backbone:

• Thermal Properties: Glass transition temperature (143°C), melting point (343°C), thermal conductivity (0.25 W/m·K), and coefficient of thermal expansion (47×10^-6/°C below Tg)

• Mechanical Properties: Flexural modulus (3.6 GPa at 23°C), compressive strength (120 MPa), and elongation at break (50%)

• Chemical Resistance: Resistant to most organic and inorganic chemicals except concentrated sulfuric acid and nitric acid. Water absorption (0.5% at saturation)

• Radiation Resistance: Maintains properties after exposure to 1100 Mrad of gamma radiation

Applications of PEEK

The unique combination of properties makes PEEK suitable for mission-critical applications across industries:

Aerospace

PEEK replaces metal components in aircraft, offering 70% weight reduction while meeting FAA flammability requirements (UL94 V-0 rating). Applications include wire insulation, bushings, and structural components in engines where temperatures exceed 200°C.

Medical

As a biocompatible material (ISO 10993 compliant), PEEK is used in spinal implants with elastic modulus (3-4 GPa) matching cortical bone. Dental instruments withstand 134°C autoclave sterilization cycles without degradation.

Oil & Gas

PEEK seals and back-up rings function in deep-well environments with 20,000 psi pressure and 250°C temperatures. Its hydrogen permeation resistance (0.5×10^-13 cm³·cm/cm²·s·Pa) prevents gas diffusion.

Semiconductor

Wafer carriers made from ultra-pure PEEK (<1 ppb metallic impurities) prevent contamination in cleanrooms. Plasma resistance exceeds 500 hours in CF₄/O₂ environments.

Industrial

PEEK gears operate at 10,000 rpm with wear rates below 0.1 mm³/Nm. Bearing cages maintain dimensional stability within ±0.02 mm under load.

Maintenance and Care

Proper handling extends PEEK component lifespan significantly:

Cleaning Procedures

• Ultrasonic cleaning: Use 40 kHz frequency with isopropyl alcohol for 5-10 minutes

• Autoclaving: Maximum 134°C for 30 minutes at 2 bar pressure

• Avoid acetone and chlorinated solvents which cause stress cracking at concentrations above 50%

Storage Conditions

• Store at <40°C and <60% RH to prevent moisture absorption

• Protect from UV exposure which causes surface embrittlement after 1000 hours of direct sunlight

• For critical components, maintain nitrogen atmosphere during storage

Operational Considerations

• Limit continuous friction applications to PV values below 3 MPa·m/s

• For sliding contacts, maintain lubrication film thickness above 0.5 μm

• In chemical environments, monitor for stress cracking after 500 hours of exposure

Machining and Fabrication

PEEK requires specialized machining techniques due to its toughness:

• Turning: Use carbide tools with 0.1-0.3 mm nose radius at 200-300 m/min cutting speed

• Milling: Maintain feed rates of 0.05-0.15 mm/tooth to prevent melting

• Drilling: Peck drilling with 118° point angle and 0.05-0.1 mm/rev feed rate

• Annealing: Stress relieve at 20°C below Tg (123°C) for 1 hour per 25 mm thickness