polycarbonate
DATE：2022/7/29 15:12:34 / READ： / SOURCE：This station
polycarbonate
Polycarbonate (PC) is the general name of polymer compounds containing carbonate links in the main chain of macromolecules. The production methods of polycarbonate include transesterification and phosgenation. At present, bisphenol A aromatic polycarbonate and engineering plastic glass fiber reinforced polycarbonate are the most widely used and widely used. (1) Properties and characteristics polycarbonate is a transparent, white or yellowish polymer, amorphous, tasteless and non-toxic; The products are rigid, impact resistant, with good toughness and low water absorption; Excellent mechanical properties. However, the fatigue strength is low and it is easy to crack; It has good heat resistance and cold resistance. The application temperature range is -60~120 ℃, the thermal deformation temperature is about 135 ℃, the temperature is 220~230 ℃, it is molten, and the decomposition temperature is >310 ℃; The melt has high viscosity, poor fluidity, difficult forming and processing, but good coloring; It has good electrical insulation, non flammable and self extinguishing; Resistant to acids, salts, oils, aliphatic hydrocarbons and alcohols, not resistant to chlorinated hydrocarbons, bases, amines, ketones and other media, and easily soluble in oxygen solvents such as dichloromethane and dichloroethane. (3) Molding method and application before molding polycarbonate products, the raw materials should be dried in a hot air circulating oven at 120~130 ℃ for about 10h to make the water content of the raw materials less than 0.03%. The raw materials after drying can be extruded, injected, blown and vacuum molded. Forming all kinds of plates, tubes, containers, films and other products. During polycarbonate molding, the temperature of the feeding section of the barrel is about 230 ℃, the temperature of the plasticizing section is about 250 ℃, the temperature of the homogenizing section is about 270 ℃, the injection pressure is within the range of 40~120mpa, and the mold temperature is about 100 ℃. In order to eliminate the internal stress of the parts, the products should be heat treated at a temperature of about 120 ℃ after forming. Polycarbonate is an engineering plastic with excellent comprehensive properties. Its products are widely used in machinery, electronic and electrical industry, transportation and textile industry, medical treatment and daily necessities. ① In terms of machinery, gears, racks, cams, worms, screws, nuts, pipe fittings, impellers, parts for valves, parts for photographic equipment and parts for clocks and watches with small workload. ② In the electronic and electrical industry, it is used as insulated connectors, coil frames, gaskets, etc. for electronic computers, televisions, radios, audio equipment and household appliances, instrument shells, hand drill shells, hair dryers, lamps and controllers, etc. ③ Daily necessities, sunglasses, lighters, smoking sets, bathtubs, helmets, lamps, tableware, signal lamp bodies, beer bottles, etc. ④ In military industry, windshield glass for aircraft, automobiles and ships, anti tank mines, gun grips, periscopes, etc. ⑤ In other aspects, such as various weft tubes, yarn tubes, wool spinning tubes, etc. used in the textile industry, glass windows and glass greenhouses with high impact strength in the construction industry and agriculture have high safety and decoration. In addition to the above properties, homoformaldehyde has high density, crystallinity and mechanical strength The short-term strength, modulus, elongation, thermal deformation temperature, creep resistance, heat culture and hot water resistance of POM are better than those of homopom, and the molding temperature range is also wide.See table 2-126 for the national standard of copolyformaldehyde. (2) Molding method and application polyoxymethylene resin can be processed by general thermoplastic molding methods, such as injection, extrusion, blow molding and spraying, but injection molding products are more widely used. The resin molded products shall be dried in an oven at 90~100 ℃ for 304H, and the water content of the resin after treatment shall not be greater than 0.1%. First extrude the resin for granulation, then add a certain proportion of filler, stabilizer and formaldehyde absorbent into the granular material, mix and stir evenly, and then extrude for granulation. Then this material can be injection molded products. During injection molding, low plasticizing temperature, short heating time, high injection pressure and injection speed should be adopted, and the mold temperature should also be taken as a high value. The heating material temperature of the barrel is 160~180 ℃, the injection pressure is 60~130mpa, and the molding mold temperature is 80~120 ℃. The formed products shall be kept in oil bath or air bath at 120~140 ℃ for 0.5~1h. Polyoxymethylene products are ideal engineering plastics. Injection molded products can replace metals such as copper, aluminum, cast zinc and steel, and are widely used in agricultural machinery, automobiles, electronic appliances, instruments and construction, light industry and other industries. For example, in automobile, it can make drainage valves, radiator tank covers, impellers in water pumps, heater fans, bearing frames, brakes and parts used on steering wheels; In mechanical equipment, it is used to make light load gears, couplings, pump housings and pump parts, machine tool guide rails and machine tool parts, etc; In terms of electrical appliances, it is used to make parts in telephones, radios, tape recorders, video recorders, televisions, electronic computers and fax machines; In daily life, it is used to make water tanks, faucets, window frames, water pipe connectors, water meter shells and parts in gas meters; Because POM is non-toxic and does not pollute the environment, it can also be widely used in food machinery and equipment, such as transmission gears, bearings and brackets.
2.8 polyethylene terephthalate
Polyethylene terephthalate (PET) is a linear polymer formed by polymerization of saturated dibasic acid and dibasic alcohol. Pet is the abbreviation of polyethylene terephthalate / alcohol ester. Polyethylene terephthalate and polybutylene terephthalate (PBT) are commonly known as thermoplastic polyester. (1) Properties and characteristics polyethylene terephthalate is transparent before drying, milky white after drying, with a density of 1.30~1.38g/cm3, amorphous glass temperature of 69 ℃, melting point of 250~265 ℃, long-term service temperature of the product of 120 ℃, low absorption rate (about 0.13%), large molding shrinkage rate of the product (about 0.7%~1%), and high step point (ignition point of 480 ℃); The product is the strongest and toughest among thermoplastic products, and has better physical and mechanical properties in a wide temperature range. The tensile strength of its film is equivalent to that of aluminum film, which is 9 times that of PE film, but its tear strength is not as good as that of PE film; 90% transparency; The electrical insulation performance is excellent, and the electrical performance is still good at high temperature and high frequency; It has good chemical resistance. It can also withstand high concentrations of hydrofluoric acid, phosphoric acid and acetic acid at high temperatures. It is not alkali resistant. It is easy to hydrolyze when boiling in hot water. (2) Molding method and application PET resin has high crystallization temperature and difficult molding processing. Generally, the film can be extruded into pieces, and then stretched vertically and horizontally. It can also be extruded or injected into blow molded containers. The film can also be vacuum plated with aluminum, copper or silver metal layers. When the film is extruded and stretched, the melt temperature is about 270 ℃, the thick film is formed with a T-shaped (or hanger shaped) mold, Quenched and shaped on the cooling roll, and then the film is stretched longitudinally (about 3 times) at a temperature of about 85 ℃, horizontally 25~4 times at a temperature of about 110 ℃, and rolled after heat setting at a temperature of about 235 ℃. PET resin is mainly used as fiber, followed by film and engineering plastics. Fibers are mainly used in the textile industry. Films are used as electrical insulating materials, such as capacitors, insulation between cables, binding materials for motors, transformers, printed circuits, wires and cables; Used as film base and baseband, such as film base, X-ray base, audio and video tape base; Various composite films are packaging materials for industrial, food, medical devices and electrical parts; In addition, the film can also be used for vacuum plating aluminum, copper or silver to make metallized film, which can be used as gold and silver wire, micro capacitor film and various decorations. Extrusion blow molding and injection blow molding packaging containers and polyester bottles have the advantages of transparency, light weight, high strength, chemical corrosion resistance, good air tightness and so on. It is used to hold all kinds of beverage bottles containing carbon dioxide gas, as well as all kinds of wine, vinegar, edible oil and cosmetics.
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