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14 kinds of engineering plastics performance and use, engineering plastics modified 8 functional

Engineering plastics generally refer to plastic materials that can be used as structural materials to withstand mechanical stress and can be used in a wide temperature range and harsh chemical and physical environments.

Engineering plastics can be divided into general engineering plastics and special engineering plastics. General-purpose engineering plastics generally refer to five types of plastics that have been widely used in industrial production and have a wide range of applications, namely, polyamide (nylon, PA), polycarbonate (polycarbon, PC), polyoxymethylene (POM), polyester (mainly PBT) and polyphenylene oxide (PPO). The special engineering plastics refer to some plastics that have outstanding performance and uniqueness, but at present, most have not yet been produced on a large scale or have a relatively small scale of production and use is relatively narrow, such as polyphenylene sulfide (PPS) and polyimide ( PI), polysulfone (PSF), polyether ketone (PEK), liquid crystal polymer (LCP), and the like. Xiao Bian describes the various types of engineering plastics in detail from three aspects: basic performance, processing performance, and use.

General engineering plastics

1, polyamide PA

Basic nature

Specific gravity: PA6-1.14g/cm3, PA66-1.15g/cm3, PA1010-1.05g/cm3;

Molding shrinkage: PA6-0.8-2.5%, PA66-1.5-2.2%;

Molding temperature: 220-300°C;

Drying conditions: 100-110 °C, 12 hours;

Material properties

Tough, wear-resistant, oil-resistant, water-resistant, and resistant to bacteria, but highly absorbent. Nylon 6 has good elasticity, high impact strength, and high water absorption; Nylon 66 has better performance than Nylon 6, high strength and good abrasion resistance; Nylon 610 is similar to Nylon 66, but has low water absorption and low rigidity; Nylon 1010 is translucent and has low water absorption. Good cold resistance.

Molding characteristics

1. The crystallization material has a high melting point, a narrow melting temperature range, and poor thermal stability. When the material temperature exceeds 300 degrees and the residence time exceeds 30 minutes, it is decomposed. More hygroscopic, need to be dry, moisture content should not exceed 0.3%;

2, good liquidity, easy to overflow. It is advisable to use self-locking nozzles and heat;

3, molding shrinkage range and shrinkage rate, obvious direction, easy to shrink hole, deformation, etc.;

4, mold temperature according to the thickness of plastic parts in the range of 20-90 degrees selection, injection pressure according to the type of injection machine, material temperature, plastic parts shape size, mold casting system selection, molding cycle by plastic wall thickness selected. When the viscosity of the resin is small, the injection and cooling time should be long, and white oil is used as a release agent;

5, the form and size of the mold casting system, increase the flow channel and gate size can reduce shrinkage.

The scope of application

Production of general mechanical parts, wear-reducing wear-resistant parts, transmission parts, and chemicals, electrical appliances, instruments, etc.

2, polycarbonate PC

Basic nature

Specific gravity: 1.18-1.20g/cm3

Molding shrinkage: 0.5-0.8%

Molding temperature: 230-320°C

Drying conditions: 110-120°C, 8 hours

Material properties

High impact strength, good dimensional stability, colorless, transparent, good coloring, good electrical insulation, corrosion resistance, wear resistance, but poor self-lubricating, stress cracking tendency, easy to hydrolyze at high temperature, poor miscibility with other resins .

Molding characteristics

1, amorphous material, good thermal stability, molding temperature range, poor fluidity. Hygroscopicity is small but sensitive to water and must be dried. Molding shrinkage is small, easy to melt cracking and stress concentration, it should be strictly controlled molding conditions, plastic parts must be annealed;

2, the high melting temperature, high viscosity, plastic parts greater than 200g should use a heated extension nozzle;

3, cooling speed, die casting system to rough, short principle, should be set up cold wells, gate should take a large, mold should be heated;

4, the material temperature is too low will cause lack of material, plastic parts dull, material temperature is too easy to overflow side, plastic foaming. When the mold temperature is low, the shrinkage rate, elongation, and impact strength are high, and the flexural, compressive, and tensile strengths are low. When the mold temperature exceeds 120 degrees, the plastic parts cool slowly, and they easily deform and stick.

The scope of application

Make instrument small parts, insulating transparent parts and impact resistant parts.

3, polyoxymethylene POM

Basic nature

Specific gravity: 1.41-1.43g/cm3

Molding shrinkage: 1.2-3.0%

Molding temperature: 170-200°C

Drying conditions: 80-90°C, 2 hours

Material properties

It has good overall performance, high strength and rigidity, good abrasion and wear resistance, small water absorption, good dimensional stability, but poor thermal stability, easy to burn, and easy to age in the atmosphere.

Molding characteristics

1. Crystalline material, narrow melting range, rapid melting and solidification, crystallization occurs when the material temperature is slightly lower than the melting temperature. Medium mobility. Hygroscopicity, can be dried without treatment;

2, low friction coefficient, good elasticity, easy to produce wrinkle pattern surface defects on the surface of plastic parts;

3, easy to decompose, decomposition temperature of 240 degrees. Irritating and corrosive gases occur during decomposition. Therefore, mold steel should be made of corrosion-resistant materials.

The scope of application

Production of wear-reducing wear parts, transmission parts, and chemical, instrumentation and other parts.

4, polyphenylene ether PPO

Basic nature

Specific gravity: 1.07g/cm3

Molding shrinkage: 0.3-0.8%

Molding temperature: 260-290°C

Drying conditions: 130°C, 4 hours

Material properties

1, as white particles. Good overall performance, can be used in 120 degree steam, good electrical insulation, low water absorption, but stress cracking tendency. Modified polyphenylene ether can eliminate stress cracking;

2. Outstanding electrical insulation and water resistance, good dimensional stability. Its dielectric properties rank first in plastics;

3. MPPO is a modified material obtained by blending PPO and HIPS. At present, materials in the market are all such materials;

4, a higher heat resistance, glass transition temperature of 211 degrees, the melting point of 268 degrees, heated to 330 degrees have a tendency to decomposition, the higher the PPO content, the better the heat resistance, heat distortion temperature up to 190 degrees;

5, good flame retardancy, self-interest, mixed with HIPS has a moderate flammability. Lightweight, non-toxic can be used in food and drug industries. Poor light resistance, long time use in the sun will change color;

6, can be modified with ABS, HDPE, PPS, PA, HIPS, glass fiber, etc.

Molding characteristics

1, non-crystalline materials, moisture absorption;

2, poor fluidity, similar to Newtonian fluid, viscosity is relatively sensitive to temperature, product thickness is generally more than 0.8mm. Easily decomposes and produces corrosive gas when decomposed. Should strictly control the molding temperature, the mold should be heated, the gating system should have a small resistance to the flow;

3, polyphenylene ether water absorption rate is very low about 0.06%, but the trace amount of moisture will cause the product surface appears silver and other non-smooth phenomenon, it is best for drying, the temperature can not be higher than 150 degrees, otherwise the color will change;

4. The polyphenylene ether molding temperature is 280-330 degrees, and the modified polyphenylene ether molding temperature is 260-285 degrees.

The scope of application

Production of heat-resistant parts, insulating parts, anti-friction wear parts, transmission parts, medical and electronic parts; gears, blades, valves and other parts that can be used at higher temperatures, can be used instead of stainless steel; screws, fastenings can be made Parts and connectors; electrical parts for motors, rotors, cases, and transformers.

5, polyethylene terephthalate PET

Basic nature

Most of the fibers used in the past, namely polyester fibers, are now rapidly developing into engineering plastics and packaging plastics. According to different uses, PET can be divided into fiber grade, film grade, blowing grade and reinforcement.

Material properties

1. It is a colorless transparent or milky white translucent solid;

2, has a high tensile strength, stiffness and hardness, but there is a certain degree of flexibility, good wear resistance, creep resistance, and can maintain these good mechanical properties over a wide temperature range;

3, with excellent electrical insulation;

4, has excellent weather resistance, outdoor exposure for six years, its mechanical properties can still maintain the initial 80%; 5, resistant to weak acids, organic solvents and oils have good chemical stability.

The scope of application

1. Making film and photosensitive film, such as film base film and photographic film;

2, as a food, medicine, textiles, precision instruments, electrical components and other packaging, the hollow container produced by its high strength, transparency, non-toxic and tasteless, is widely used in carbonated beverages, beer, edible oil and other plastic packaging materials; electrical material;

3, for the production of a variety of electrical insulation materials, such as wires, switches, electrical enclosures.

6. Polybutylene terephthalate PBT

Basic nature

PBT used as engineering plastics are unmodified and modified. Unmodified grades have high molding shrinkage and mechanical properties are inferior to other engineering plastics, so they are rarely used alone. Nearly 80% of PBT is modified.

Material properties

1. It is a milky white crystalline solid, odorless, odorless, nontoxic, and has a shiny surface. The flexibility is better than PET, and the melting temperature and rigidity are relatively small;

2, with excellent electrical insulation. Even in wet and harsh environments;

3, have good weather resistance;

4, can resist the general chemical corrosion, such as weak acid.

The scope of application

1. Make all kinds of auto parts, such as door handles, bumpers, rearview mirror housings, etc.;

2, the production of electrical and electronic parts, such as connectors, sockets, plugs, fuse boxes, etc.;

3, making a variety of electrical enclosures and components, such as telephones, indoor and outdoor lighting appliances shell, hair dryer components.

7, ultra-high molecular weight polyethylene UHMWHPE

Basic nature

The relative molecular mass exceeds 1.5 million, and the comprehensive performance is a special engineering plastic that conventional molecular weight polyethylene does not possess. The molecular structure is exactly the same as that of ordinary polyethylene, but the molecular weight is particularly high. In UHMWPE with a relative molecular weight of more than 1.5 million, there are also grades with a relative molecular mass of 2 million, 3 million, and even up to 5 million or more.

Material properties

1, the average molecular weight of about 350,000 to 8 million, due to the high molecular weight and other plastics have unmatched excellent impact resistance, wear resistance, self-lubricating properties, chemical resistance and other properties;

2, excellent low temperature resistance, still high impact strength at -40 °C, even at -269 °C;

3, with electrical insulation, low water absorption and physiological inertia;

4, has excellent stress crack resistance, creep resistance and fatigue resistance.

The scope of application

It is used in machinery, transportation, textile, papermaking, mining, agriculture, chemical industry and sports equipment, among which the large-scale packaging containers and pipelines are the most widely used; it has also been used as a heart valve or orthopedic surgical part because of its excellent physiological inertia. , artificial joints, etc. used in clinical medicine.

8, thermoplastics

Polyacrylonitrile-Butadiene-Styrene ABS

Basic nature

Specific gravity: 1.05g/cm3

Molding shrinkage: 0.4-0.7%

Molding temperature: 200-240°C

Drying conditions: 80-90°C, 2 hours

Material properties

1、Comprehensive performance, high impact strength, good chemical stability, good electrical performance;

2, with 372 organic glass welding is good, can be made of two-color plastic parts, and can be chrome plated, spray paint treatment;

3, high impact, high heat resistance, flame retardant, enhanced, transparent and other levels;

4, liquidity is slightly worse than HIPS, better than PMMA, PC, etc., good flexibility.

Molding characteristics

1, amorphous material, medium fluidity, moisture absorption, must be fully dry, the surface of the plastic parts required to be shiny and preheated dry 80-90 degrees, 3 hours;

2, should take high material temperature, high mold temperature, but the material temperature is too high and easy to decompose (decomposition temperature is> 270 degrees), for high precision plastic parts, mold temperature should take 50-60 degrees, high gloss, resistance to Thermoplastics, mold temperature should take 60-80 degrees;

3, if you need to solve the water mark, you need to improve the fluidity of the material, take a high material temperature, high mold temperature, or change the water level and other methods;

4, such as the formation of heat-resistant grade or flame-retardant material, 3-7 days after the mold surface will remain plastic decomposition products, resulting in shiny mold surface, the need to clean the mold in time, while the mold surface needs to increase the exhaust position.

The scope of application

Produce general mechanical parts, wear-reducing wear parts, transmission parts and telecommunications parts.

Special engineering plastics

1. Polyphenylene sulfide PPS

Basic nature

Specific gravity: 1.36g/cm3

Molding shrinkage: 0.7%

Molding temperature: 300-330°C

Material properties

1. Excellent electrical insulation (especially high-frequency insulation), white, hard and brittle, falling on the ground with metal noise, light transmittance second only to plexiglass, coloring water resistance, good chemical stability. Excellent flame retardancy, for non-combustible plastics;

2, the general strength, rigidity is very good, but the crisp, easy to produce stress embrittlement; not resistant to benzene, gasoline and other organic solvents; long-term use temperature of up to 260 degrees, in 400 degrees of air or nitrogen remain stable. By adding glass fiber or other reinforcing materials, the impact strength can be greatly improved, the heat resistance and other mechanical properties can be improved, the density can be increased to 1.6-1.9g/cm3, and the molding shrinkage can be reduced to 0.15-0.25. %.

Molding characteristics

1, amorphous material, moisture absorption, but should be dried after molding;

2. The fluidity is between the ABS and the PC, and the solidification is quick, the shrinkage is small, and the decomposition is easy. The injection pressure and the injection speed are selected to be higher. The mold temperature is 100-150 degrees. The main channel taper should be large and the flow channel should be short.

The scope of application

Production of heat-resistant parts, insulating parts and chemical instruments, optical instruments and other parts. Such as: televisions, computer high-voltage components, housings, motor starting coils, blades, brush holders and rotor insulation components, relays, electric irons, F-class films. In the automotive sector, exhaust gas recirculation valves and pump impellers, bearings, and sensing components can be manufactured.

2, polysulfone PSF or PSU

Basic nature

Specific gravity: 1.25-1.35g/cm3;

Molding shrinkage: 0.5-0.7%

Molding temperature: 290-350°C

Drying conditions: 130-150°C, hour

Material properties

1. Polysulfone is amber transparent solid material, high hardness and impact strength, non-toxic, heat and cold resistance, good aging resistance, can be used at -100--175 degrees for a long time. Resistant to the corrosion of inorganic acid and alkali salts, but not resistant to aromatics and halogenation;

2, through the glass fiber reinforced modification can make the material's wear resistance greatly improved;

3. Polysulfone and ABS, polyimide, polyether ether ketone and fluoroplastic can be made into modified products of polysulfone, mainly to improve its impact strength and elongation, solvent resistance, environmental resistance, and processing. Performance and platability. Such as PSF/PBT, PSF/ABS, PSF+ mineral powder.

Molding characteristics

1, amorphous material, moisture absorption, water absorption rate of 0.2% -0.4%, must be fully dried before use, and to prevent reabsorption. Guaranteed moisture content below 0.1%;

2. The molding performance is similar to that of the PC, and the thermal stability is poor. The decomposition begins at 360 degrees.

3, poor fluidity, cooling fast, it is appropriate to use high temperature and high pressure molding. The mold should have sufficient strength and rigidity, set up the cold material well, the flow channel should be short, and the gate size should be 1/2-1/3 of the wall thickness of the plastic part;

4, in order to reduce the internal stress generated by injection molding products, mold temperature should be controlled at 100-140 degrees. After forming, annealing treatment with glycerin bath can be used, 160 degrees for 1-5 minutes; or take an air bath of 160 degrees for 1-4 hours. Annealing time depends on the size and wall thickness of the product;

5, polysulfone in the molten state close to Newtonian body, similar to polycarbonate, fluidity is relatively sensitive to temperature, in the 310 degrees -420 degrees, the temperature rises by 30 degrees, the flow increases by 1 times. Therefore, during the molding process, the fluidity is improved mainly by increasing the temperature.

The scope of application

1, suitable for the production of heat-resistant parts, insulation, wear-resistant wear-resistant parts, instrumentation parts and medical equipment parts, also applies to the production of low-temperature working parts;

2. Polysulfone is commonly used in the electronic and electrical industry to manufacture integrated circuit boards, coil pipe racks, contactors, case racks, capacitive films, and high-performance alkaline battery cases;

3. Polysulfone is used in microwave ovens, coffee heaters, humidifiers, hair dryers, cloth dryers, beverages and food dispensers in household appliances. Can also replace non-ferrous metals for precision watches, copiers, cameras, etc.;

4. Polysulfone has passed the relevant regulations in the field of medicine and food in the United States. It can replace stainless steel products and used as a surgical tool tray, sprayer, fluid controller, heart valve, pacemaker, gas mask, and dental tray.

3, fluorine plastic

Fluoroplastics are paraffinic polymers in which part or all of the hydrogen is replaced by fluorine, and they include polytetrafluoroethylene (PTFE), perfluoroethylene propylene (FEP) copolymer, polyperfluoroalkoxy (PFA) resin, polytrifluoro Vinyl chloride (PCTFF), ethylene chlorotrifluoroethylene copolymer (ECTFE), ethylene tetrafluoroethylene (ETFE) copolymer, polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF).

Polytetrafluoroethylene PTFE

Basic nature

Specific gravity: 2.1-2.2g/cm3

Molding shrinkage: 3.1-7.7%

Molding temperature: 330-380°C

Material properties

1, long-term use temperature -200 - 260 degrees, has excellent chemical resistance, corrosion resistance to all chemicals, the lowest coefficient of friction in plastic, there are very good electrical properties, its electrical insulation is not subject to temperature Influence, there is the name of "plastic king";

2. It is transparent or translucent. The higher the crystallinity, the worse the transparency. Most of the raw materials are powdered resins or concentrated dispersions, which have a very high molecular weight and are highly crystalline thermoplastic polymers.

Molding characteristics

1, crystallization material, moisture absorption;

2. Poor fluidity, easy to decompose and produce corrosive gases when decomposed. Should strictly control the molding temperature, the mold should be heated, the gating system should have a small resistance to the flow;

3, powdered resin often used powder powder metallurgy molding, the use of sintering methods. The sintering temperature is 360-380 degrees and must not exceed 475 degrees. Emulsion resins are usually processed by a cold extrusion and re-sintering process to form an anti-corrosion layer on the surface of the article. If it is required to have transparency and good toughness, rapid cooling should be adopted. Can also adopt extrusion molding, can extrude tubes, rods, profiles;

4, PTFE melt viscosity is very high, the volume viscosity decreases with the increase of shear stress, showing the characteristics of non-Newtonian fluid; 5, secondary processing, can be hot pressed composite, welding, bonding, reinforcement, machining Etc. to make the final product.

The scope of application

Produce corrosion-resistant parts, wear-resistant wear parts, seals, insulation parts and medical equipment parts.

Teflon-ethylene copolymer ETFE

Basic nature

Specific gravity: 1.7g/cm3

Molding shrinkage: 3.1-7.7%

Molding temperature: 300-330°C

Material properties

1, long-term use temperature -80 - -220 degrees, has excellent chemical resistance, corrosion resistance to all chemicals, the lowest coefficient of friction in plastic, there are very good electrical properties, its electrical insulation is not subject to temperature Influence, there is the name of "plastic king";

2. Its chemical resistance is similar to PTFE and better than vinylidene fluoride;

3, its creep resistance and compressive strength are better than PTFE, high tensile strength, elongation up to 100-300%, good dielectric properties, excellent radiation resistance.

Molding characteristics

1, crystallization material, moisture absorption is small. It can be processed into finished products by the method of processing thermoplastics.

2. Poor fluidity, easy to decompose and produce corrosive gases when decomposed. Should strictly control the molding temperature does not exceed 350 degrees, the mold should be heated to 100-150 degrees, the gating system on the flow resistance should be small. Formable 0.7-0.8mm thick thin-walled simple products; 3, transparent pellets, injection molding, extrusion molding. Molding temperature 300-330 degrees, 350 degrees or more easily cause discoloration or bubbles. Should be high-speed low-pressure molding, and pay attention to demoulding will be more difficult.

The scope of application

1, suitable for the production of corrosion-resistant parts, wear-resistant wear parts, seals, insulation and medical equipment parts;

2, wire, cable insulation, anti-corrosion equipment, sealing materials, valve bushings, and chemical containers.

Soluble polytetrafluoroethylene PFA

Basic nature

Specific gravity: 2.13-2.167g/cm3

Molding shrinkage: 3.1-7.7%

Molding temperature: 350-400°C

Material properties

1. A small amount of copolymer of perfluoropropyl perfluorovinyl ether and polytetrafluoroethylene. The melt adhesion increases, the viscosity of the solution decreases, and the performance does not change compared to PTFE. The resin can be directly processed into products using ordinary thermoplastic molding methods;

2, long-term use temperature -80 - 260 degrees, has excellent chemical resistance, corrosion resistance to all chemicals, the lowest coefficient of friction in plastic, there are very good electrical properties, its electrical insulation is not subject to temperature Influence, there is the name of "plastic king";

3. Its chemical resistance is similar to PTFE and better than vinylidene fluoride;

4, its creep resistance and compressive strength are better than PTFE, high tensile strength, elongation up to 100-300%. Good dielectric properties, excellent radiation resistance. Flame retardant up to V0.

Molding characteristics

1, crystallization material, moisture absorption is small. It can be processed into finished products by the method of processing thermoplastics.

2. Poor fluidity, easy to decompose and produce corrosive gases when decomposed. Should strictly control the molding temperature should not exceed 475 degrees, the mold should be heated to 150-200 degrees, the gating system on the flow resistance should be small;

3, transparent pellets, injection molding, extrusion molding. Molding temperature 350-400 degrees, 475 degrees or more easily cause discoloration or bubbles. And notice that demoulding will be more difficult;

4, due to the molten material on the metal corrosion, long-term production, molds need to electroplating chromium.

The scope of application

1, suitable for the production of corrosion-resistant parts, wear-resistant wear parts, seals, insulation and medical equipment parts;

2, high temperature wire, cable insulation, anti-corrosion equipment, sealing materials, valve bushings, and chemical containers.

4. Poly(aryl ether ketone) PEAK

Polyaryletherketone (PEAK) is a type of polymer in which a phenylene ring is linked by an ether bond and a carbonyl group. At present, there are polyether ether ketone (PEEK), polyether ketone (PEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK) and polyether ketone ketone ketone (PEKEKK) and other varieties. In the polyaryletherketone series, the lower the ratio (E/K) of the ether bond to the keto group in the molecular chain, the higher the melting point and the glass transition temperature. The ether bond in the polyaryletherketone molecular structure makes it flexible, so it can be processed by the processing method of thermoplastic engineering plastics.

Material properties

1, has a good high temperature performance, long-term use temperature above 240 °C;

2, high mechanical properties. Excellent chemical resistance, good resistance to radiation, resistant to 10 gamy gamma radiation;

3, the combustion performance can reach UL94V-0 level, and the amount of smoke when burning is very small and non-toxic, the heat released when burning is also very small, which is a very important technical performance of the aircraft interior trim;

4, in a wide range of operating temperature and frequency within a good electrical performance, low dielectric loss under high frequency, is an excellent high temperature, high strength C-class electrical insulation material.

The scope of application

1. It is mostly used in the field of high-tech aerospace or some of the structural components of the automobile industry, electrical and electronic industry and machinery industry where the technical requirements are more demanding;

2. Various connectors for flame resistance and oil resistance on aircraft; weather resistant and creep resistant radome;

3, for the automotive industry and machinery industry in a variety of components can withstand dynamic loads, such as bearing retainers, gears, hot water pumps, turbine blades, wear-resistant seal rings;

4. In medical devices, PPEK manufactures heaters and pressure sensor housings for hemodialysis machines and dental instruments that require disinfection and sterilization. PPEK can also replace metals to make human bones. The potential application prospects are very attractive.

5. Polyarylate PAR

Basic nature

Specific gravity: 1.2-1.26g/cm3

Molding shrinkage: 0.8%

Molding temperature: 300-350°C

Drying conditions: 100-120°C, 5 hours

Material properties

1. It is a transparent amorphous thermoplastic engineering plastic with excellent heat resistance, flame retardancy and non-toxicity. It can be directly processed into products using ordinary thermoplastic molding methods;

2, with excellent thermal properties, under the load of 1.86MPA, the heat distortion temperature of up to 175 degrees, the decomposition temperature of 443 degrees. Its various mechanical properties are less affected by temperature.

Molding characteristics

1. As the product wall thickness increases, the molding shrinkage increases;

2, Hygroscopicity is small, about 0.1-0.3%, but the trace amount of moisture during injection can cause the polyarylate to decompose. Therefore, the material must be dried before it is molded. Its water content is less than 0.02%;

The scope of application

1, suitable for making heat-resistant, flame-resistant and high dimensional stability of electrical components. Connectors, coil formers, relay housings;

2, lighting parts. Can be made of transparent lampshade, lighting, automotive reflectors and so on

6, liquid crystal polymer LCP

Liquid crystal polymer refers to a polymer material that can form a liquid crystal state under certain conditions, abbreviated as LCP, and is one of the fastest-growing new materials in recent years. Can be divided into lyotropic (LLCP) and thermal induced (TLCP) two categories. Thermotropic liquid crystals are liquid crystals in the molten state, which are mainly used as engineering plastics. According to the temperature class can be roughly divided into super heat-resistant, heat-resistant, low heat-resistant three.

Material properties

1. LCP is a high-strength, high-modulus, creep-resistant, high-impact high-molecular material, its mechanical properties are much higher than ordinary engineering materials;

2. Outstanding wear resistance, high surface hardness and low wear. Molding shrinkage is very small, excellent processing fluidity. Thermal stability and heat resistance are high. Excellent electrical insulation;

3, with excellent chemical stability, is also very stable to ultraviolet radiation. With outstanding flame retardancy, it is generally no need to add flame retardant to achieve UL94V-0 level of flame retardant, smoke is also very low;

4, also has excellent vibration absorption characteristics, used as acoustic parts can reduce noise.

The scope of application

1. High-density connectors, bobbin holders, bobbins, sockets, etc.; loudspeaker vibration boards and headphone switches in audiovisual devices; floppy disks, hard disk drives, and copies of office equipment;

2, in the chemical industry, for a variety of devices and components. Such as distillation column packing, valves, oil well equipment, etc.;

3, in the aerospace, aviation, military industry and other cutting-edge technology fields, there is a wide range of application prospects. Such as the use of its high temperature, flame retardant, low smoke characteristics, can be used for various parts of the aircraft;

4, for medical devices has a unique advantage. Due to the low invasiveness of surgical instruments of LCP materials, it will become the master of medical miniaturization technology;

5, LCP other microwave oven stove containers, packaging materials, sports equipment.

7, polyimide PI

Polyimide, abbreviated as PI, is the earliest high-temperature, high-strength special engineering plastics. In the heat-resistant engineering plastics, it occupies an extremely important position, and is a general term for aromatic heterocyclic polymers containing an imide group in the main chain of the molecule. The varieties that have been industrially produced and scaled are mainly styrene-type polyimide, polyamide-imide (PAI), polyetherimide (PEI) and bismaleimide (BMI).

Material properties

1, excellent mechanical properties, high tensile strength, creep resistance, wear resistance is also very good;

2, excellent heat resistance, long-term use temperatures are above 200 °C. The low temperature resistance is also outstanding, and the mechanical strength can be maintained at a low temperature of -269°C.

3, is a flame-retardant polymer, low combustion smoke density, toxic gas content is small;

4, excellent radiation resistance, corona resistance is superior to other engineering plastics.

The scope of application

Aircraft engine parts, aircraft internal structural parts, etc.; high-strength and dimensional stability of civil industrial and military sockets, electronic instruments and some high-performance working parts of household appliances; engine pistons, connecting rods, speed control gear and some other high temperature Precision parts. It is also suitable for the manufacture of medical vessels, medical devices that require multiple sterilizations, and some working parts that require extremely low temperatures, even in contact with liquid nitrogen.

With the continuous improvement of the modification technology, high-performance and new functionalized modified plastics are gradually replacing ordinary plastics and other materials and are widely used in home appliances, office equipment, automobiles, and machinery and chemical industries. Common eight functional modified engineering plastics.

1, wear-resistant modified engineering plastics

Wear-resistant modified engineering plastics can provide a lower coefficient of friction to reduce the wear rate. For example, the lid of a blood glucose meter can increase its back-and-forth service life when used with a wear-resistant material. At the same time, wear-resistant modified engineering plastics are also used in color matching products, even between different materials. In disposable products such as needles and blades also benefit from the lubricating effect of the material. In addition, other applications for wear resistant materials include catheters, cannulas, transmissions, and vacuum tubes. Other effects include reduced noise due to the movement of smooth parts, improved processing and production of plastics and extrusion molding efficiency.

Wear-resistant polyetheretherketone is a kind of special engineering plastics with excellent comprehensive performance. It is not only wear-resistant, but also has excellent heat resistance, chemical resistance, radiation resistance, electrical properties, flame retardancy, etc. It is widely used in automobiles. , electronic appliances and machinery, chemical and other fields.

Polyformaldehyde wear-resistant, but also creep resistance, chemical resistance, hardness, polysilicon wear-resistant polyformaldehyde products used in automobiles, electronic appliances and household appliances.

2, conductive modified engineering plastics

When the thermoplastic material adds a conductive component, it has a permanent electrostatic dissipation (ESD) and prevents electrostatic accumulation to provide protection. Conductive thermoplastics allow the release of electrostatic continuity rather than rapid accumulation and discharge. Static electricity can damage sensitive electronic components and can cause an explosion in a flammable environment. Accumulated static electricity can block the transmission of the material and interrupt the mechanical transmission. Conductive thermoplastic materials can be widely used in color matching products, and some conductive materials are transparent. Its use mainly includes, ECG sensors, pipettes, electrical protection devices and new medical delivery devices, such as inhalation products, including PMDI spacers.

3, spray-free modified engineering plastics

Spray-free plastic is a special pearl powder or metal pigment added to a specific resin. It is modified through the use of special compatible technologies. Direct injection molding can achieve various pearlescent, colorful or metallic appearance effects, and successfully solve special colors. Effects For many years in the injection molding products, there are difficult problems in the welding lines or flow marks, which meet the market trend of colorful texture, low consumption, high efficiency, and environmental protection and energy saving. Through the provision of personalized customized appearance color design, so that consumers get a good visual experience and safety and environmental protection.

Compared to traditional spray-painted plastics, spray-free plastics can be molded at one time, and aesthetic plastics with beautiful appearance can be obtained without painting. It has the characteristics of greener, more environmentally friendly, lower cost, higher design freedom and fewer process problems.

4, carbon fiber modified engineering plastics

Carbon fiber-based modified engineering plastics are mainly reinforced. They are composite materials formed by using carbon fiber or carbon fiber fabric as reinforcement and PA/PC/ABS/PBT/PPO as matrix. Mainly used in automotive manufacturing, electrical and electronic appliances, household appliances, sports equipment and other fields requiring high strength, high modulus, low specific gravity, anti-static, friction and other areas, including: automotive features, printers, detectors, electronic trays, Textile machine thread shuttle and so on.

5, antibacterial modified engineering plastics

Antibacterial modified engineering plastics are plastics that inhibit or kill bacteria, molds, alcohol mother bacteria, algae and even viruses that are stained on plastics in the use environment. They keep themselves clean by inhibiting the reproduction of microorganisms. . At present, antimicrobial plastics are mainly obtained by adding a small amount of antibacterial agent to the matrix plastic.

6, light diffusion type modified engineering plastics

Light diffusion materials are generally made by adding a light diffusing agent to a transparent resin to achieve a soft light effect. The light diffusion material includes light diffusion PC and light diffusion PMMA. The material has the characteristics of high transmittance, high haze, and good weather resistance, and is widely used in the fields of LEDs, electronic appliances, home appliances and the like.

7, magnetic modified engineering plastics

The composite magnetic plastic is a material obtained by mixing a magnetic powder with a plastic binder, supplemented with an appropriate auxiliary agent. Magnetic plastics are widely used in many fields such as electronics, electrical, instrumentation, communications, culture, education, health care and daily life. Their output and demand are constantly increasing, and they have great potential for development.

8, thermal conductivity of modified engineering plastics

Thermal conductive plastic is the use of thermally conductive filler (including particles, fibers, plies, etc.) to uniformly fill the polymer matrix material to improve its thermal conductivity. The thermal conductivity is mainly measured by the thermal conductivity (unit: W/(m.k)). At present, the application of thermally conductive plastics in the LED field is the most extensive. In addition, heat-conducting plastics are also used in pipes, heat exchangers, automobiles, heating/cooling/refrigeration and the like.