7 reinforcement materials to improve the wear resistance of plastics
Wear resistance is an important indicator that determines the application field and service life of plastics. In order to reduce the friction and wear of plastics, you can choose to add lubricating substances or reinforcing substances.
Lubricating oil has many shortcomings. After a long time, the grease will age, it also needs frequent maintenance, and it is easy to gather dust and debris and contaminate internal parts.
Therefore, adding reinforcing materials to increase the wear resistance and self-lubricating properties of plastics has become the best choice.
Common additives and reinforcing materials are: polytetrafluoroethylene (PTFE), molybdenum disulfide, ultra-high molecular weight polyethylene, silicon, graphite, glass fiber, carbon fiber, aramid fiber, etc.
1. Polytetrafluoroethylene (PTFE, Teflon)
Polytetrafluoroethylene (PTFE), commonly known as Teflon, was invented by DuPont in 1938.
PTFE hardly adheres to any substance, and at the same time has self-lubricating properties, so it is usually used as an anti-stick coating. Non-stick coating is a classic application of PTFE.
PTFE powder is specially used as an additive. It has the lowest coefficient of friction among all friction-resistant additives. During the friction process, PTFE powder will form a lubricating film on the surface of the part. It is the best anti-wear additive in high-load applications. The most appropriate amount of PTFE added is 15% PTFE for non-crystalline plastics and 20% PTFE for crystalline plastics.
PTFE powder can be used in engineering plastics, coatings, inks, paints, lubricants, films, rubber, etc., to enhance the performance of the main material, such as:
1. Wear resistance, friction resistance and scratch resistance
2. Easy to decontaminate
3. Anti-blocking properties
4. Lubrication performance (used for engineering plastic modification)
5. Anti-friction and anti-wear performance
2. Molybdenum disulfide
Molybdenum disulfide (MoS2) is a black powder with metallic luster and a slippery touch. Molybdenum disulfide is an important solid lubricant, especially suitable for high temperature and high pressure, and is known as the "king of advanced solid lubricants". In the field of engineering plastics, it is mainly used as a wear-resistant additive for nylon plastics.
The chemical structure of graphite is a unique lattice structure. This unique chemical structure makes it easy for graphite molecules to slide against each other with little friction. This abrasion resistance is especially important in environments with water. This characteristic makes graphite an ideal abrasion resistance additive for many applications placed in water, such as water paving shells, impellers and value seals.
Polysiloxane fluid is a migratory wear-resistant additive. When added to thermoplastics, the additive will slowly migrate to the surface of the part and form a continuous film. Polysiloxanes have a wide range of viscosity. The viscosity of polysiloxane is extremely low, and it moves to the surface of the part quickly and in a fluid state to provide abrasion resistance. If the viscosity of the polysiloxane is too low, it will be more volatile and will quickly disappear from the part.
5. Glass fiber
Glass fiber is an inorganic non-metallic material, mainly made of silica, with a diameter of a few microns to more than 20 microns. It has the advantages of good insulation, strong heat resistance, good corrosion resistance and high mechanical strength. It is often used as a reinforcing material for plastics.
Although glass fibers are inherently brittle and have poor wear resistance, if used to reinforce plastics, glass fibers can provide the function of strong mechanical bonding between polymers, so glass fibers can increase the integrity of the thermoplastic structure and improve wear resistance.
Glass fiber reinforced plastics can be applied to various mechanical parts such as: water pumps, water valves, bearings, bushings, gears, brackets, rollers, etc.
6. Carbon fiber
Carbon fiber is made of viscose yarn, polyacrylonitrile fiber and pitch yarn as raw materials and carbonized at 300~1000℃.
As in the case of glass fiber, carbon fiber can greatly improve the integrity of the structure, abrasion resistance, and the ability to withstand load and abrasion speed. Unlike glass fiber, carbon fiber is a softer and less scratchy fiber. Carbon fiber will not scratch the friction surface of iron steel or steel with which it rubs.
Taking advantage of the self-lubricating properties of carbon fiber, carbon fiber reinforced plastic can be used for special-purpose bearings, gears and piston rings. Such as oil-free lubricated bearings for aviation instruments and tape recorders, oil-free lubricated gears for electric drive diesel locomotives (to avoid accidents caused by oil leakage), and oil-free lubricated piston rings on compressors.
7. Aromatic polyamide fiber (aramid)
Aramid fiber, commonly known as aramid, has been successfully developed by DuPont in the United States since the 1960s. It is a new type of high-tech synthetic fiber with super high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and other excellent properties. Its strength is 5-6 times that of steel wire.
Aramid fiber is also one of wear-resistant additives. Compared to glass fiber and carbon fiber, it is the softest and least scratch-free fiber. This feature is the main advantage of aramid fiber in wear-resistant applications, especially the scratch-resistant fiber on the surface of mating parts.