Polytetrafluoroethylene (
PTFE) is a special engineering plastic, with good physical and chemical properties, capable of "king water", commonly known as "plastic king". PTFE has a very wide temperature range and can be used continuously for a long time between 180-250 ° C. Its coefficient of friction is very low, only 0.04, non-absorbent, non-flammable. However, due to the non-polar molecular chain of PTFE, the mechanical properties of PTFE are poor. Using the excellent friction and high temperature performance of PTFE, using other engineering plastics with high mechanical strength to blend and modify it, can synthesize the advantages of each component, achieve complementary advantages, and produce excellent performance of engineering plastic friction materials, thus expanding the application field of engineering plastics. Commonly used engineering plastics blended with PTFE are the following:
1
Polyformaldehyde (POM)
POM is a highly crystalline linear thermoplastic polymer, with unique mechanical properties, excellent oil resistance, chemical resistance, creep resistance and good thermal and electrical properties, low water absorption, can maintain its mechanical, chemical and electrical properties in a wide temperature range, is a kind of engineering plastics with excellent comprehensive properties. By modifying POM with PTFE, the defects of POM with poor toughness and low notched impact strength can be improved, and excellent friction materials can be prepared.
2
Polyether ether ketone (PEEK)
PEEK has excellent comprehensive performance, good heat resistance, long-term use temperature up to 240 ° C, fiber reinforced grade up to 300 ° C, but also has high strength, high rigidity, creep resistance and good fatigue resistance, as well as self-flame retardant, oil resistance, organic solvent resistance and other characteristics. Since its advent in the 1960s, PEEK and its composite materials have been widely used in aviation, aerospace, electronics and other industrial fields. Glass fiber (GF)/ carbon fiber (CF) hybrid reinforced PEEK/PTFE composite is a kind of wear-resistant material with excellent comprehensive properties, and has the advantages of high temperature resistance, wear resistance, etc., which can be used as structural components in high temperature environment.
3
Polyphenylene Sulfide (PPS)
PPS is a new type of engineering plastic pioneered by the American Phillip Oil Company in 1968. Known as the "new plastic for the jet age", PPS has outstanding thermal stability, good adhesion, electrical insulation, corrosion resistance and self-extinguishing. Its disadvantage is that the impact resistance is poor, and the molding process is difficult. The inert surface of PTFE makes the sum of PPS difficult to bond, domestic scholars use PPS powder and mixing agent mixed ball milling and then add PTFE powder to make coating. PTFE/PPS alloy coating solves the problem that PPS melt flow rate is high and it is difficult to be molded directly. It can still maintain high mechanical properties above 300 ° C, mainly used for corrosion-resistant pumps, fluxes, gaskets, and dynamic seals, bushings, automotive engine valve covers, chromatograph sliding seals and guides.
4
Polyamide (
PA)
The addition of PTFE to PA mainly improves its slippability. When the PTFE filling amount is greater than 10%, the anti-friction and wear resistance of PA is also improved, and the friction coefficient and wear amount are greatly reduced.
5
Polyimide (PI)
PI is a general term for polymers containing imide groups on the main chain, and is a representative of heterocyclic polymer compounds first industrialized production by the United States Dupont company. It has outstanding heat resistance, radiation resistance and wear resistance, and products made of thermoplastic polyimide (TPI) and PTFE blending or adding other fillers can be used in automotive engine cover parts, aerospace equipment and office electronics.
