Engineering plastics refer to plastics that can be used as engineering materials and substitute for metal to make machine parts. Engineering plastics have excellent comprehensive properties and can be used for a long time in harsh chemical and physical environments. They can replace metals as engineering structural materials. Compared with general plastics, engineering plastics meet higher requirements in terms of mechanical properties, durability, corrosion resistance, and heat resistance, of which the processing is more convenient to replace metal materials. Engineering plastics are widely used in electronic and electrical, automotive, construction, office equipment, machinery, aerospace and other industries.
Classification & Applications:
Engineering plastics can be divided into general engineering plastics and special engineering plastics. The main varieties of the former are five general engineering plastics of polyamide, polycarbonate, polyformaldehyde, polyphenylene ether, and thermoplastic polyester. The latter mainly refers to engineering plastics with heat resistance above 150℃. The main varieties are polyimide, polyphenylene sulfide, polysulfone, aromatic polyamide, polyarylate, polyphenyl ester, polyaryl ether ketone, liquid crystal polymer and fluororesin, etc.
- General engineering plastics: (1) Polyamide: In fact, polyamide, often called nylon, is also one of the most popular engineering plastics, which has good mechanical properties, durability, corrosion resistance, and heat resistance. Most importantly, its processing is also very convenient, and it has been widely used in the automotive, membrane, electronic, and electrical industries. (2) Polycarbonate: The most important feature of polycarbonate is that it has metal-like strength, good ductility, and toughness. As it looks very much like glass with good transmittance, it is often used as lighting glass, lampshade, signal lights, windshield, and so on, which is one of the most widely used engineering plastics at present. (3) Polyformaldehyde: Polyformaldehyde is one of the most promising engineering plastics, because it has the same hardness and strength as metal to replace some metal parts. It can be widely used in electronic and electrical, machinery, instrumentation, daily light industry, automobile, building materials, agriculture, and other industries. (4) Polyphenylene ether: Polyphenylene ether can replace stainless steel in the manufacture of surgical and medical instruments, and can also be used in the manufacture of parts in some electronic and electrical industries, such as gears, blower blades, pipes, valves, molds, and so on.
Figure 1. Preparation of "Turing" structure polyamide Membrane.
Figure 2. Synthesis of polycarbonate.
- Special engineering plastics: (1) Polyimide: Due to the properties and synthetic chemistry, polyimides stand out among many aromatic heterocyclic polymers and become a very important engineering plastics. It is widely used in films, coatings, fibers, high temperature resistant, and heat insulating materials, adhesives, microelectronic devices, electro-optical materials, and humidity sensitive materials. (2) Polyphenylene sulfide: Polyphenylene sulfide, referred to as PPS, is often mixed used with other materials, which has good heat resistance, corrosion resistance, and flame retardancy to a certain extent. (3) Polysulfone: Polysulfone is a thermoplastic resin with sulfone group (-SO2-) and arylene group in the molecular main chain. It is usually used in the machinery industry (such as hot water valves for food machinery, freezing system appliances, and transmission parts), electronic and electrical appliances (made of various high-temperature resistant coil frames, switches, and connectors), transportation (hot air ducts and frame windows on aircraft.), and medical devices (gas masks, endoscope parts, artificial heart valves, artificial dentures, blood pressure tubes, dental mirror scaffolds, and syringes).
Figure 3. Structural formula of polysulfone.
- Zhai H B.(2009) “PPA Improves the Performance of Automobile Fucl System.” Automobile Technology & Material. 9(6):68-72.
- Wu W, CAO K K. (2018) “Preparation and characterization of MXD6 Type Copolymerized Nylon.” China Plastics Industry. 46(8):51-54.