What Is Plastics Engineering?

Engineering plastics can be used as engineering materials and plastics instead of metal manufacturing machine parts. ^[1] Engineering plastics have excellent comprehensive properties, high rigidity, small creep, high mechanical strength, good heat resistance, and good electrical insulation. They can be used for a long time in harsh chemical and physical environments, and can replace metals as engineering Structural materials are used, but the price is more expensive and the output is smaller. ^[2]

Chinese name: Engineering Plastics
Foreign name: engineering-plastics

Main varieties: Polyamide, polyphenylene sulfide, polycarbonate, etc.
Main performance: Thermal properties, etc.

Classification of Engineering Plastics

Engineering plastics can be divided into two categories: general engineering plastics and special engineering plastics. The main varieties of the former are five general engineering plastics: polyamide, polycarbonate, polyformaldehyde, modified polyphenylene ether, and thermoplastic polyester; the latter mainly refers to engineering plastics with a heat resistance of more than 150 ° C. The main varieties are polyimide. , Polyphenylene sulfide, polysulfones, aromatic polyamides, polyarylates, polyphenylene esters, polyaryletherketones, liquid crystal polymers, and fluororesins.

Main properties of engineering plastics

The performance characteristics of engineering plastics are mainly:

(1) Compared with general-purpose plastics, it has excellent heat resistance and cold resistance, excellent mechanical properties in a wide range of temperatures, and is suitable for use as a structural material;

(2) Good corrosion resistance, less environmental impact, and good durability;

(3) Compared with metal materials, it is easier to process, has higher production efficiency, and can simplify procedures and save costs;

(4) Good dimensional stability and electrical insulation;

(5) Light weight, high specific strength, and outstanding friction reduction and wear resistance.

A brief history of engineering plastics

Engineering plastics only developed rapidly in the 1950s. Although nylon 66 resin has been successfully developed and put into production as early as 1939, it was mainly used to manufacture synthetic fibers at that time. It did not break through the traditional use of pure fibers until the 1950s, and made plastics through molding. The rapid development of engineering plastics really came after the successful development of polyoxymethylene and polycarbonate in the late 1950s. Their emergence is of special significance. Due to the high crystallinity of polyoxymethylene, it has given it excellent mechanical properties, and for the first time, plastic has been among the structural materials as a material that can replace metals. With the successful development of co-formaldehyde and the popularization of screw injection molding machines in the future, the important position of engineering plastics in the field of materials is further established. Polycarbonate is a transparent engineering plastic with excellent comprehensive properties. It is widely used and is one of the fastest-growing engineering plastics. In the field of engineering plastics, its output and consumption rank second only to polyamide.

In 1961, the United States DuPont successfully developed polyimide, which opened the way to the development of special engineering plastics. The emergence of polyimide has also promoted the development of many heat-resistant engineering plastics such as polysulfone, polyphenylene sulfide, and polybenzimidazole, which have had a profound impact on the development of the plastic industry.

American General Company put the polyphenylene ether resin it developed into industrial production in 1964.

In 1980, the British ICI company successfully developed a special engineering plastic polyetheretherketone (PEEK) with a melting point of up to 336 ° C. PEEK has attracted widespread attention due to its excellent heat resistance, radiation resistance, and chemical resistance, and its ability to be injection molded. Composites made of PEEK as a matrix and reinforced with glass fibers or carbon fibers have been used in the aerospace and aerospace fields.

The successful development of thermotropic liquid crystal polymers in the mid-1980s was another major event in the history of the development of specialty engineering plastics. Liquid crystal polymer is excellent in heat resistance. It can be used at temperatures above 200 ° C. It has self-reinforcement, high strength, high modulus, and chemical resistance. It has low melt viscosity and convenient molding. prospect. ^[2]

Engineering plastic applications

Compared with general plastics, engineering plastics can meet higher requirements in terms of mechanical properties, durability, corrosion resistance, heat resistance, etc., and they are more convenient to process and can replace metal materials. Engineering plastics are widely used in electronic and electrical, automotive, construction, office equipment, machinery, aerospace and other industries. Plastic instead of steel and plastic instead of wood have become an international trend. Engineering plastics has become the fastest-growing field in the plastic industry in the world today. Its development not only supports the national pillar industries and modern high-tech industries, but also promotes the transformation of traditional industries and the adjustment of product structures.

Engineering plastics are increasingly used in automobiles, mainly used as bumpers, fuel tanks, instrument panels, body panels, doors, lamp covers, fuel pipes, radiators, and engine-related parts.

Mechanically, engineering plastics can be used for mechanical parts such as bearings, gears, screw nuts, seals, and mechanical structures such as housings, covers, handwheels, handles, fasteners, and pipe joints.

In electronic appliances, engineering plastics can be used for insulation materials such as wire and cable coatings, printed circuit boards, insulating films, and electrical equipment structural parts.

In household appliances, engineering plastics can be used in refrigerators, washing machines, air conditioners, televisions, electric fans, vacuum cleaners, electric irons, microwave ovens, rice cookers, radios, combined audio equipment and lighting appliances.

In the chemical industry, engineering plastics can be used in chemical equipment such as heat exchangers, chemical equipment linings, and pipes and fittings, valves, pumps and other chemical pipelines.

Due to the rapid development of China's automotive, electronics and construction industries, China has become the country with the fastest growing global demand for engineering plastics. According to analysis, with the continuous development of the domestic economy, the demand for engineering plastics will further increase, and the development prospect of China's engineering plastics industry is very broad. As far as the home appliance industry is concerned, the annual demand for engineering plastics for refrigerators, freezers, washing machines, air conditioners and various small household electrical appliances will reach about 600,000 tons. The amount of engineering plastics used in communications infrastructure construction and railway and highway construction is even more alarming. It is expected that the total demand in the next few years will reach more than 4.5 million tons.

In 2010, the consumption of engineering plastics in China reached 2.443 million tons, an increase of 11% year-on-year, and it was the fastest growing country in the world. In 2011, the consumption of engineering plastics in China was 2.72 million tons, an increase of 11.34% year-on-year. It is estimated that by 2013 China's consumption of engineering plastics will reach 3.37 million tons, and in 2015 it will reach 4.17 million tons.

Engineering plastics applications (4 photos)

Development prospects of engineering plastics

According to a Markets and Markets research report, the global market value of engineering plastics in 2013 was approximately US $ 53.58 billion, and it is expected to reach US $ 79.03 billion by 2018, with a compound annual growth rate of 8%.

Engineering plastics have a wide range of applications due to their excellent stability, good heat and chemical resistance, and high strength, and their demand continues to grow rapidly. One of the main uses of engineering plastics is to replace the application of metals in various end industries. In particular, increasingly stringent environmental regulations require automobiles to reduce emissions and improve fuel economy, and engineering plastics are being widely used in the automotive and transportation industries. In addition, engineering plastics are also widely used in consumer and home appliance products, electrical and electronic products, industrial machinery, packaging, and medical and construction industries.

In 2014, the Asia-Pacific region occupied the main body of the global engineering plastics market. According to statistics, the Asia-Pacific region accounted for 47.9% of the global engineering plastics market demand in 2013. It is expected that the Asia-Pacific region will continue to maintain its position as the world's largest engineering plastics market in 2018, followed by the Western European market. In the next five years, the average annual growth rate of its engineering plastics market demand is expected to be 7.8%. ^[3]

Main varieties of engineering plastics

Engineering plastics mainly include polycarbonate (Polycarbonate, PC), polyamide (Polyamide, PA), polyacetal (Polyacetal, Polyoxy Methylene, POM), polyphenylene oxide (Polyphenylene Oxide, PPO), polyester (PET, PBT ), Polyphenylene sulfide (Polyphenylene Sulfide, PPS), polyarylate and so on.

Engineering plastic polyamide

Polyamide (PA, common name: Nylon) has attracted people's attention due to its unique low specific gravity, high tensile strength, wear resistance, good self-lubrication, excellent impact toughness, and both rigid and flexible properties. In addition, its processing is simple and efficient High, light weight (only 1/7 of metal), can be processed into various products instead of metal, widely used in automotive and transportation industries. Typical products include pump impellers, fan blades, valve seats, bushings, bearings, various instrument panels, automotive electrical meters, hot and cold air conditioning valves and other components. Each car consumes 3.6 to 4 kg of nylon products. Polyamide is the largest consumer in the automotive industry, followed by electronics and electronics.

Different purposes of polyamide modification, polyamide modification can be divided into types such as strengthening, toughening, flame retardant, filling and alloy. The research on polyamide nanocomposites has also made great progress.

In order to obtain a polyamide material with higher strength and heat distortion temperature, inorganic or organic fibers or fillers are added to the polyamide matrix, and a high-strength polyamide composite material is prepared by a blend extrusion method. There are many varieties of reinforced PA, and almost all polyamide materials can be made into reinforced varieties.

The main commercial varieties are: enhanced PA6, enhanced PA66, enhanced PA46, enhanced PA1010, enhanced PA610, etc. Among them, the largest yield is enhanced PA6 and PA66. Commonly used polyamide reinforcement materials are glass fibers, carbon fibers, and aramid fibers. Inorganic whiskers are also used to reinforce polyamides.

Engineering plastic polyphenylene sulfide

Referred to as PPS.

The outstanding properties of PPS are: good heat resistance, can be used in the temperature range of 180 ~ 220 ; corrosion resistance is close to polytetrafluoroethylene; excellent electrical properties; excellent mechanical properties;

The disadvantages of PPS are: the price is too high, which is a low price among high temperature resistant plastics, but much higher than general engineering plastics; poor toughness and brittleness; the viscosity is unstable during processing. Pure PPS is rarely used alone due to its brittleness, and the PPS used is a modified variety. Specifically: 40% glass fiber reinforced PPS (R4), inorganic filled PPS (R8), carbon fiber reinforced PPS (G6), etc. PPS is used for 45% of automobiles, 30% for electronics and electrical appliances, and 25% for others. The development of PPS is fast, and it is expected to become the sixth largest engineering plastic.

Engineering plastic polycarbonate

Polycarbonate (PC) not only has the strength similar to non-ferrous metals, but also has the ductility and strong toughness. Its impact strength is extremely high. It cannot be destroyed by hammering with a hammer, and it can withstand the explosion of the TV screen. Polycarbonate has excellent transparency and can be applied with any coloration. Due to the above-mentioned excellent properties of polycarbonate, it has been widely used in various safety lampshades, signal lights, transparent protective plates for stadiums and stadiums, lighting glass, high-rise building glass, automobile reflectors, windshield plates, aircraft cabin glass, and motorcycles. Car driving helmet. The most heavily used markets are computers, office equipment, automobiles, alternative glass and sheet, and CDs and DVDs are one of the most promising markets.

Engineering plastic polyformaldehyde

Polyoxymethylene (POM) is a kind of engineering plastic with excellent performance. It is known as steel grabber and super steel in foreign countries. POM has similar hardness, strength and rigidity as metal. It has good self-lubrication, good fatigue resistance and elasticity in a wide range of temperature and humidity. In addition, it has good chemical resistance. Character. At a lower cost than many other engineering plastics, POM is replacing some markets traditionally occupied by metals, such as replacing zinc, brass, aluminum, and steel to make many parts. Since its inception, POM has been widely used in electronics, electrical, and machinery. , Instrumentation, daily light industry, automotive, building materials, agriculture and other fields. In many new fields of application, such as medical technology, sports equipment, etc., POM has also shown a good growth trend.

PBT Engineering Plastic PBT

Polybutylene terephthalate (PBT) is a thermoplastic polyester. Compared with other thermoplastic engineering plastics, non-reinforced PBT has better processing and electrical properties. PBT has a low glass transition temperature, and can crystallize quickly at a mold temperature of 50 ° C, with a short processing cycle. Polybutylene terephthalate (PBT) is widely used in the electronics, electrical, and automotive industries. Due to the high insulation and temperature resistance of PBT, it can be used as a flyback transformer for televisions, car distribution boards and ignition coils, office equipment housings and bases, various automotive exterior parts, air conditioner fans, electronic stove bases, office Equipment shells.

Engineering plastic polyphenylene ether

Referred to as PPO. It has excellent comprehensive performance. The biggest feature is that under long-term load, it has excellent dimensional stability and outstanding electrical insulation. It has a wide temperature range and can be used for a long time in the range of -127 121 . Has excellent water and steam resistance, products with higher tensile strength and impact strength, creep resistance is also good. In addition, it has good abrasion resistance and electrical properties. It is mainly used to replace stainless steel to make surgical medical equipment. In the mechanical and electrical industry, it can make gears, blower blades, pipes, valves, screws and other fasteners and connectors. It is also used to make parts in the electronics and electrical industries, such as coil bobbins and printed circuit boards.

Polyphenylene ether