Physical properties and applications of polyimide (PI) and polytetrafluoroethylene

Physical properties and applications of Polyimide (PI) and Polytetrafluoroethylene

The physical characteristics and product application of Polyimide Block PI sheet Rod products:

1. Ultra-high temperature and ultra-low temperature resistance: the operating temperature is -272 ~ +360°C, and the high temperature can reach 500°C in an instant.

2. Wear resistance: the PV critical value of non-lubricated conditions is more than 10 times that of general engineering plastics, and it can resist strong impact and vibration wear.

3. Deformation and creep resistance: It will not soften at high temperature and can withstand high loads. The creep value at 300℃ and 18.2MPa for 1000 hours is only 0.6%.

4. Resistant to plasma and various rays.

5. Ultra-vacuum application: It has excellent sealing performance, which can reach 10-10Torr., and has excellent machining performance.

Widely used in aircraft, aviation, automobiles, office equipment, electronic and electrical equipment, scientific instruments, industrial machinery and production equipment, etc., which require temperature resistance, wear resistance, sealing, dimensional stability and deformation without breaking. The product includes sealing rings, Thrust washers, sliding bearings, vacuum pump blades, valve seats, gears, etc.

Polyimide products can be simply divided into PI pure material products and PI composite material products:

1. PI pure material products

100% pure polyimide resin can be molded, injection molded and extruded. It has excellent comprehensive properties, high mechanical properties, excellent electrical and thermal insulation properties, high temperature resistance, wear resistance (high PV value) and excellent size stability. Product applications mainly include environments with high comprehensive requirements for mechanical properties, purity, heat insulation and insulation, and friction coefficients. Typical applications include valve seats, mold heat insulation caps, plasma torch swirl rings, timing gear tensioners, and printer paper. Separation claw, brake pad sensor positioner, etc.

2. PI composite products

2-1 PI and PTFE composite products

It is molded with 15% polytetrafluoroethylene PTFE and polyimide PI resin to improve the wear resistance of the product and make the size more stable. Typical applications mainly include high-temperature seals, support rings, guide wear rings, compressor piston rings, heat-resistant gears, etc., and finished products such as gear pumps and copiers.

2-2 PI and graphite composite products

Molded with 15% graphite and polyimide PI resin, it has excellent wear resistance under high PV value conditions. Product applications mainly include various sealing rings and sealing rings, various sliding bearings. Typical applications include thrust gaskets, sealing rings, piston sealing rings, hydraulic motor sealing rings, EGR automotive exhaust gas recovery bushings, Turbocharger bushing holders, miniature dental bushing holders, vacuum pump and air tool blades, etc.

Molded with 40% graphite and polyimide PI resin, it has a very low coefficient of linear expansion and low coefficient of friction. It is suitable for the application environment with wide working temperature range and high requirements on the dimensional stability of parts, as the material of high-pressure sealing rings and sealing rings, such as sealing rings of hydraulic motors and hydraulic boosters.

2-3 Composite products of PI, graphite and PTFE

Molded with 15% graphite, 10% PTFE and polyimide PI resin, it has an extremely low friction coefficient and is suitable for high-speed working conditions.

The product application is mainly for piston sealing rings and sealing rings. Due to its excellent wear resistance and dimensional stability, it has extremely high reliability for sealing gas.

2-4 Composite products of PI and molybdenum disulfide

Molded with 15% molybdenum disulfide and polyimide PI resin, it has excellent wear resistance and sealing performance in high vacuum environment. The product use environment includes the application of ultra-vacuum and outer space environment, and can be made into valve seat and bayonet.

Composite materials of PI and molybdenum disulfide are also widely used in centrifugal pumps and enter industries such as oil refineries, chemical plants, power plants and other fluid handling equipment. This composite material is used as the mouth ring, throat bushing and bearing of the pump, which can replace other composite materials such as metal, graphite and silicon carbide, significantly improve the efficiency and reliability of the pump, and improve the operation performance of the pump, which can effectively reduce the cost of the pump. The probability of jamming during operation can be reduced by more than 50%.

2-5 PI and diamond resin composite products:

Ultrafine polyimide PI resin can be used as a bonding agent for diamond grinding wheels and heavy-duty resin grinding wheels. It does not produce low molecular volatiles during curing, has good compatibility with various fillers, high bonding strength, and unique flexibility. , can withstand the test of large feed, the production efficiency is 35~50% higher than that of phenolic resin grinding wheel, and the service life is increased by more than 2 times. Due to its excellent wear resistance, heat resistance, moderate melt fluidity, and convenient forming and processing, Widely used in production processes that require high strength, high and low temperature resistance, high electrical insulation and self-lubricating machinery and aerospace parts.