PEEK’s molecular structure contains a large number of rigid benzene rings, so its heat resistance is very good, which can rival that of polyimide (PI), while two ether bonds and a carbonyl group provide the material with good flexibility .
PEEK is expensive. Generally, domestic PEEK is several hundred yuan per kilogram, and imported PEEK is more than one thousand yuan per kilogram. The high cost of PEEK is inseparable from its outstanding performance. Compared with other resin materials, PEEK has excellent performance in high temperature resistance, mechanical properties, stability, corrosion resistance, aging resistance and peek CNC machining performance. Its main properties are summarized as follows :
1. High Temperature Resistance
PEEK is one of the thermoplastic materials with the best heat resistance, with a melting point of 334 °C (similar to PTFE), and the long-term use temperature of UL certification in the United States is 260 °C, even when the temperature reaches 300 °C, it can still maintain excellent mechanical properties. The heat deformation temperature of PEEK is 135~160℃, the heat deformation temperature of 20% glass fiber reinforced PEEK is 286℃, and that of 30% glass fiber reinforced is 300℃.
2. Heat-Resistant Aging
PEEK has outstanding thermal aging properties. The following figure shows the performance retention rate of VICTREX®450G after thermal aging at 200°C and 310°C. Even if it is thermally aged in steam at 200°C for 10,000 hours, the tensile strength, quality and appearance of PEEK are not good. Significant changes will occur.
3. Good Mechanical Properties
PEEK has excellent mechanical properties and is the most perfect combination of toughness and rigidity among all resins. PEEK has high rigidity, its strength and fatigue resistance are comparable to some metals and alloy materials, PEEK can maintain high strength even at high temperature, the flexural strength at 200℃ can reach 24MPa, and the flexural strength and compression at 250℃ The strength can reach 12~13 MPa, which is especially suitable for the manufacture of components that work continuously at high temperatures.
PEEK has a small linear expansion coefficient (close to metal aluminum) and good dimensional stability. In addition, PEEK also has good creep resistance, can withstand great stress during the service life, and will not cause significant extension due to the extension of time.
4. Wear-Resistant And Self-Lubricating
PEEK resin itself has excellent self-lubrication and wear resistance. The friction coefficient of the filled resin can be reduced to 0.15, and the wear amount is extremely low, which can realize oil-free lubrication work, and can be used in many harsh environments such as high temperature, high load, and strong corrosion. Under high pressure, PEEK polymers and their composites have excellent wear resistance and are excellent bearing materials.
5. Chemical Resistance
In addition to the corrosion of strong oxidizing acids such as high concentrations of concentrated sulfuric acid, PEEK is resistant to almost any chemicals, and it can still maintain good chemical stability even at higher temperatures.
6. Hydrolysis Resistance
PEEK has good hydrolysis resistance, and the saturated water absorption at 23°C is only 0.5%. Among all engineering plastics, PEEK has the best resistance to hot water and steam. It can be used in long-term steam at 200°C, or short-term in high-pressure steam at 300°C.
7. Flame Retardant, Low Smoke
PEEK has excellent flame retardancy and self-extinguishing properties. Without any additives, the flammability rating of PEEK rapid prototyping samples with a thickness of 1.45mm is UL94 V-0; the flammability rating of PEEK samples with a thickness of 3.2mm is UL94 5V class. Even when burning, the amount of smoke and toxic gases produced is extremely small, far lower than other types of resins.
8. Electrical Insulation
PEEK resin is an ideal electrical insulator, which can still maintain good electrical insulating properties under harsh working conditions such as high temperature, high pressure and high humidity. Usually, the volume resistivity can reach 1015~1016Ω·cm, the dielectric constant is 3.2~3.3F/m, the dielectric loss is 0.0016 at 1kHz, the breakdown voltage is 17Kv/mm, and the arc resistance is 175V.
9. Good workability
PEEK has high thermal decomposition temperature and good fluidity at high temperature, so it has good processability and can be processed in a variety of ways: injection molding, peek extrusion molding, compression molding, blow molding, melt spinning, rotational molding, powder coating Wait.
10. Radiation Resistance
The ability of PEEK to resist gamma radiation is very strong, surpassing that of polystyrene, which has the best radiation resistance among general-purpose resins. insulation capacity.
11. Resistance to peeling and fatigue
PEEK resin is very resistant to peeling, so it can be made into very thin wire or magnet wire and used in harsh conditions. Of all resins, PEEK has the best fatigue resistance.