Polybutylene terephthalate
DATE：2022/7/30 9:27:20 / READ： / SOURCE：This station
Polybutylene terephthalate
Polybutylene terephthalate (PBT) is a crystalline thermoplastic. The relative density is 1.31~1.55, the melting point is about 225 ℃, and the water absorption is one of the lowest among thermoplastics, only 0.07%; Excellent strength, toughness and fatigue resistance, high impact strength. Low friction coefficient and self lubrication; Good heat resistance and weather resistance, not easy to burn, but can burn hungry; The electrical property is excellent, and the volume resistivity is 1016 Ω· cm, which is 190s higher than the arc resistance of general engineering plastics, and is also the highest among plastics; Good chemical resistance, stable to organic bath agents, gasoline, engine oil, general cleaners, etc., except for the decomposition of strong oxidizing acids such as concentrated nitric acid, concentrated sulfuric acid and alkaline substances; The size is stable, but it is sensitive to notch impact. The molding method and application are similar to pet, but the reinforced PBT resin is mainly used.2.10 wind gathering
Polysulfone, also known as bisphenol-A polysulfone (PSF), is a high-performance thermoplastic engineering plastic made by polycondensation of bisphenol A and dichlorodiphenylsulfoxide dimethyl sulfoxide. (1) Properties and characteristics polysulfone is a slightly amber transparent amorphous complex. It has excellent mechanical properties, high strength, good impact resistance, wear resistance, fixed size, good creep resistance, small molding shrinkage, and can be used as precision parts, but it is easy to stress crack; Good thermal stability, can be used in the temperature range of -100~150 ℃, and the tear strength can reach 190 ℃ for short-term use; The products are non-toxic, radiation resistant, flame-retardant and self extinguishing; Good dielectric properties, even in water and humid air, it will maintain high dielectric properties; It has good chemical stability. Except for concentrated sulfuric acid and concentrated nitric acid, it is stable to other acids, bases, alcohols, aliphatic hydrocarbons and other chemicals, but it will swell in esters and ketones, and some of it will dissolve, and it is easy to dissolve in biennial methane and dichloroethane. The linear energy of weather resistance and UV resistance is poor. See table 2-130 for PSF performance parameters. (2) Molding method and application polysulfone can be processed and molded by injection, extrusion, molding, blow coating, thermoforming, electric welding, welding and other methods. Raw materials need to be dried and exploded at 135 ℃ for 3.5H. After molding, post-treatment should be carried out at a temperature of about 155 ℃ to eliminate the internal stress of the product, and then slowly reduce to room temperature. Products mainly include machinery industry accessories, such as gears, impellers, pump bodies, washing machine accessories, etc; Relays, coil frames, instrument panels, contactors, insulating parts in transformers, TV parts, etc. in electrical and electronic industries; Split speed cover, battery cover ignition parts, sensors, etc. in the automotive industry; Acid resistant nozzles, valves, pipelines, containers, etc. in the chemical industry; Household appliances and medical equipment accessories, etc.
2.1.1 polystyrene
Polyphenylene oxide (PPO), also known as polyphenylene oxide, is a high temperature resistant thermoplastic resin. Polyphenylene oxide is non-toxic, transparent and low density; It has good comprehensive performance, high strength, good stress relaxation resistance, creep resistance, stable size and good heat resistance. The maximum thermal deformation temperature can reach 190 ℃, which can be used for a long time in the temperature range of -90~150 ℃. The glass transition temperature is 211 ℃, the melting point is 268 ℃, and the decomposition phenomenon occurs at 330 ℃; Light weight, good flame retardancy, self extinguishing and poor light resistance; Poor melt fluidity and difficult molding (PPO blends or alloys are generally used, that is, modified MPPO); It is resistant to dilute acid, dilute alkali and salt solutions, and not resistant to strong oxidizing acids. Chain hydrocarbons, ketones and esters make products crack under stress; Soluble in aromatic hydrocarbons or chlorinated chain hydrocarbons. Polyphenylene oxide can be used for injection, extrusion and molding, as well as foaming, blow molding and fusion molding. The main products are electronics, electrical appliances, automobiles, machinery, household appliances, chemical and medical equipment accessories. Such as sockets, winding racks, instrument enclosures, accessories, weak current machine accessories, connectors, silent gears, clock measuring instruments, well pumps, hot water meters, copiers, typewriters, blades, sprinklers, valves, surgical instruments and disinfection instruments.
2.1.2 auxiliary materials
Auxiliary materials for plastics refer to some additives added to the main raw material resin to improve the performance of the resin or plastic products before the processing of various plastic resins. Some auxiliary materials can change the processing performance of the resin, some can improve the physical and mechanical properties of the products, and some can change the appearance and quality of plastic products. According to these functions of additives, they are classified into commonly used plastic additives, plasticizers, stabilizers, processing aids, impact modifiers, antioxidants, light stabilizers, combustion agents, foaming agents, antistatic agents, colorants, lubricants, fillers, cross-linking agents, etc.2.12.1 precautions for use selection
① The additives should have good compatibility with the resin, and be able to be separated in the products for a long time and stably, without volatilization, exudation and frost spraying, so as to maintain the quality of the products. ② It does not decompose and deteriorate under high temperature conditions, and has no corrosive effect on machinery and equipment. ③ The mixed application of various additives does not produce mutual antagonism and does not reduce the original function of each additive. ④ Choose additives with low toxicity and little impact on environmental pollution. ⑤ The selected additives should be efficient and cheap.
2.12.2 plasticizers
Adding plasticizer to the resin can change the plasticity of the material, make it soft, reduce the melt viscosity and improve the molding processing characteristics. The properties and applications of common plasticizers are as follows. ① Dibutyl phthalate (DBP) is a colorless transparent liquid, toxic and solubleMost organic solvents have a ignition point of 202 ℃. It is used in PVC products to make the products have better softness. ② Dioctyl phthalate (DOP) is a colorless oily liquid with a special smell. Its ignition point is 241 ℃, and it can be dissolved in most organic solvents. It is the main plasticizer of PVC products, with good comprehensive properties: mixing performance, low softness, electrical insulation, heat resistance, weather resistance are good, and the plasticization efficiency is high, which can be used in food packaging fat formation. ③ Diisooctyl phthalate (Diop) is a colorless and viscous liquid, which can be dissolved in most organic solvents and hydrocarbons, and the ignition point is 249 ℃. Its performance is close to that of DOP and can replace DOP. It has low toxicity and low price, but its electrical performance, plasticizing efficiency and low temperature performance are slightly worse than that of DOP. ④ Dioctyl adipate (DOA) is a colorless, odorless liquid, non-toxic, boiling point 210 ℃ (655pa), ignition point 235 ℃, insoluble in water, soluble in most organic solvents. It is a cold resistant plasticizer in PVC products. The products still have good softness in low temperature environment. At the same time, they also have light stability and water resistance. They can be used as forming aids for food packaging materials, but their volatility and electrical insulation are insufficient. ⑤ Di-n-butyl sebacate (DBS) is a colorless liquid, non-toxic, ignition point 218 ℃, explosion limit in air 0.44% (volume fraction, lower limit at 243 ℃), solubility in water 0.40g/l (20 ℃). It is compatible with most resins, has good solvent effect, and can be used as cold resistant main plasticizer; It is often used in combination with phthalates to reduce its volatility and the possibility of being easily extracted by water, soapy water and washing solutions. ⑥ Dioctyl sebacate (DOS) is a colorless oily liquid with a ignition point of 263 ℃. It is soluble in organic solvents such as alcohol, benzene and ether, but insoluble in water. It is a cold resistant plasticizer with good low-temperature performance and low volatility, which is often used in cable materials. It can also be used in high-temperature environment, with good weather resistance and electrical insulation; However, it is easy to be extracted by hydrocarbon solvents and easy to migrate. ⑦ Trimethylbenzene phosphate (TCP) is colorless, slightly phenolic, toxic, decomposes at 420 ℃, has a flash point of 230 ℃, and is soluble in benzene, ether and alcohol. It has excellent compatibility with PVC and can be used as the main plasticizer of PVC. It has good flame retardancy, wear resistance, weather resistance and electrical properties, low volatility, water and oil extraction resistance, but poor low temperature performance. ⑧ Triphenyl phosphate (TPP) is a white acicular crystal with a melting point of 49.2 ℃. It is toxic and insoluble in water. It is a kind of flame retardant auxiliary plasticizer, which has good mechanical properties, good flexibility, strength and toughness, and low volatility; Poor light resistance, not suitable for light colored products. ⑨ Butyl epoxy stearate (BES or BeO) is a light yellow transparent liquid. When the temperature is lower than 10 ℃, a small amount of condensate precipitates, and the flash point is greater than 190 ℃, which is soluble in organic solvents such as chloroform. It has good compatibility with PVC. It is both a plasticizer and a stabilizer. It has good heat resistance, weather resistance and cold resistance; But it is volatile, and the dosage is about 5%. ⑩ Benzene sulfonate (m-50) is a yellow oily transparent liquid with a flash point of 200-220 ℃ (open dish) and is used in PVC products. It has good dielectric properties, mechanical properties, weather resistance and low volatility; However, the cold resistance is poor, and the compatibility is medium. When used, it is often used together with phthalates, generally about 15 phr. ⑪ Chlorinated paraffin (43%) is a golden yellow or amber viscous liquid, non-toxic, tasteful, non flammable, non explosive, extremely volatile, soluble in most organic solvents, insoluble in alcohol and alcohol, and can decompose hydrogen chloride gas when the temperature is greater than 120 ℃. Metal chemicals such as iron and zinc can promote its decomposition. It can be used as an auxiliary plasticizer of PVC, replacing some main plasticizers, reducing product costs and flammability.
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