From history to application, understand the past and present life of engineering plastics

1、 What is engineering plastics?

Engineering plastics are plastics that can be used as engineering materials and replace metals to make machine parts. Engineering plastics have excellent comprehensive properties, high rigidity, low 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. They can replace metals as engineering structural materials, but the price is expensive and the output is small.

2、 Classification of Engineering Plastics:

Engineering plastics can be divided into general engineering plastics and special engineering plastics. The former mainly includes polyamide, polycarbonate, polyformaldehyde, modified polyphenylene ether and thermoplastic polyester; The latter mainly refers to engineering plastics with heat resistance above 150 ℃, and the main varieties include polyimide, polyphenylene sulfide, polysulfone, aromatic polyamide, polyarylene ester, polyphenylene ester, polyarylene ether ketone, liquid crystal polymer and fluororesin.

3、 Development history of Engineering Plastics:

Engineering plastics developed rapidly in the 1950s. Although nylon 66 resin had 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 processing. Engineering plastics really developed rapidly after the successful development of polyoxymethylene and polycarbonate in the late 1950s. Their emergence is of great significance. Due to the high crystallinity of polyoxymethylene, it is endowed with excellent mechanical properties, which makes plastics rank among the ranks of structural materials as a material that can replace metals for the first time. Later, with the successful development of CO formaldehyde and the popularization of screw injection molding machine, the important position of engineering plastics in the field of materials was further established. Polycarbonate is a transparent engineering plastic with excellent comprehensive properties. It is widely used and is one of the fastest developing engineering plastics. In the field of engineering plastics, its output and consumption are second only to polyamide.

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

General Motors put its polyphenylene ether resin into industrial production in 1964.

In 1980, British ICI company successfully developed a special engineering plastic polyether ether ketone (PEEK) with a melting point of 336 ℃. Peek has excellent heat resistance, radiation resistance and chemical resistance, and can be injection molded, so it has attracted widespread attention. The composites made of PEEK as matrix and reinforced by glass fiber or carbon fiber have been applied in the field of aviation and aerospace.

The successful development of thermotropic liquid crystalline polymers in the mid-1980s is another major event in the development history of special engineering plastics. Liquid crystal polymer has excellent heat resistance, the service temperature can reach more than 200 ℃, has the characteristics of self reinforcement, high strength, high modulus, chemical resistance, low melt viscosity and convenient molding. It has a very broad application prospect in the field of electronic industry.

4、 Development status of engineering plastics in China:

Due to the rapid development of China’s automobile, electronics and construction industries, China has become the country with the fastest growing demand for engineering plastics in the world. According to the analysis, with the continuous development of domestic economy, the demand for engineering plastics will further increase, and the development prospect of China’s engineering plastics industry is very broad. In the household appliance industry, the annual demand for engineering plastics for refrigerators, freezers, washing machines, air conditioners and all kinds of small household appliances will reach about 600000 tons. The amount of engineering plastics used in communication infrastructure construction, railway and highway construction is even more amazing. It is expected that the total demand will reach more than 4.5 million tons in the next few years.

In 2010, China’s consumption of engineering plastics reached 2.443 million tons, with a year-on-year increase of 11%, which is the country with the fastest growth in global demand; In 2011, the consumption of engineering plastics in China was 2.72 million tons, with a year-on-year increase of 11.34%. It is estimated that the consumption of engineering plastics in China will reach 3.37 million tons in 2013 and 4.17 million tons in 2015.

5、 Main performance characteristics of Engineering Plastics:

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

 (2) Good corrosion resistance, less affected by the environment and good durability;

 (3) Compared with metal materials, it is easy to process, has high production efficiency, simplifies the program and saves costs;

 (4) Good dimensional stability and electrical insulation;

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

6、 Main applications of Engineering Plastics:

Compared with general plastics, engineering plastics can meet higher requirements in mechanical properties, durability, corrosion resistance and heat resistance, and can be processed more conveniently and replace metal materials. Engineering plastics are widely used in electronic and electrical, automotive, construction, office equipment, machinery, aerospace and other industries. Replacing steel with plastic and wood with plastic has become an international popular trend. Engineering plastics has become the fastest growing field in the world’s plastic industry. Its development not only supports the national pillar industry and modern high-tech industry, but also promotes the transformation of traditional industries and the adjustment of product structure.

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

In machinery, engineering plastics can be used for mechanical parts such as bearings, gears, lead screws, nuts and seals, as well as mechanical structural parts such as shell, cover plate, hand wheel, handle, fasteners and pipe joints.

In electronic and electrical appliances, engineering plastics can be used for wire and cable coating, printed circuit board, insulating film and other insulating materials and structural parts of electrical equipment.

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 sound equipment and lighting appliances.

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