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20 plastic characteristics
-20 plastic properties
Polymers and mixtures of PC/ABS polycarbonate and acrylonitrile-butadiene-styrene
Typical application scope: computer and commercial machine shell, electrical equipment, lawn gardening machine, automobile parts dashboard, interior decoration and wheel cover).
Process conditions of injection mold: drying treatment: drying treatment before processing is necessary. The humidity should be less than 0.04%, and the recommended drying condition is 90~ 1 10C for 2~4 hours. Melting temperature: 230 ~ 300 C. Mold temperature: 50 ~100 C. Injection pressure: depends on plastic parts. Injection speed: as high as possible.
Chemical and physical characteristics: PC/ABS has the comprehensive characteristics of PC and ABS. For example, the processability of ABS and the excellent mechanical properties and thermal stability of PC. The ratio of the two will affect the thermal stability of PC/ABS materials. PC/ABS composites also show excellent flow characteristics. The shrinkage rate is about 0.5%.
A mixture of PC/PBT polycarbonate and polybutylene terephthalate
Typical applications: gear boxes, automobile bumpers and products requiring chemical resistance, corrosion resistance, thermal stability, impact resistance and geometric stability. Technological conditions of injection mold: drying treatment: it is recommended to dry at 1 10~ 135C for about 4 hours. Melting temperature: 235 ~ 300 degrees Celsius. Mold temperature: 37 ~ 93 degrees Celsius. Chemical and physical characteristics: PC/PBT has the comprehensive characteristics of PC and PBT, such as high toughness and geometric stability of PC, chemical stability, thermal stability and lubrication characteristics of PBT. The shrinkage rate is about 0.5%.
Typical application scope of PE-HD high density polyethylene: refrigerator container, storage container, household kitchenware, sealing cover, etc.
Injection mold process conditions: drying: if stored properly, it is not necessary to dry. Melting temperature: 220 ~ 260 degrees Celsius. For materials with larger molecules, it is suggested that the melting temperature range is 200~250C C and the mold temperature is 50 ~ 95 C. Plastic parts with wall thickness less than 6mm should adopt higher mold temperature, and plastic parts with wall thickness greater than 6mm should adopt lower mold temperature. The cooling temperature of plastic parts should be uniform to reduce the shrinkage difference. In order to obtain the best machining cycle time, the diameter of the cooling channel should be not less than 8mm, and the distance from the die surface should be within 1.3d (where "d" is the diameter of the cooling channel). Injection pressure: 700~ 1050bar. Injection speed: high-speed injection is recommended. Runner and gate: the diameter of runner is between 7.5mm, and the length of runner is as short as possible. Various types of gates can be used, and the gate length should not exceed 0.75 mm. Especially suitable for using hot runner mold.
The high crystallinity of PE-HD leads to its high density, tensile strength, high temperature deformation temperature, viscosity and chemical stability. PE-HD has stronger permeability resistance than PE-LD. PE-HD has low impact strength. The characteristics of PH-HD are mainly controlled by density and molecular weight distribution. The molecular weight distribution of PE-HD suitable for injection molding is very narrow. For the density of 0.9 1~ 0.925g/cm3, we call it the first kind of PE-HD; For the density of 0.926~ 0.94g/cm3, it is called the second kind of PE-HD; For the density of 0.94~ 0.965g/cm3, it is called the third kind of PE-HD. The flow characteristics of this material are very good, and the MFR is between 0. 1-28. The higher the molecular weight, the worse the flow characteristics of PH-LD, but the better the impact strength. PE-LD is a semi-crystalline material, and the shrinkage rate after molding is high, which is 1.5%-4%. PE-HD is prone to environmental stress cracking. By using materials with very low flow characteristics to reduce internal stress, the cracking phenomenon can be alleviated. When the temperature is higher than 60C, PE-HD is easily soluble in hydrocarbon solvents, but its solubility resistance is better than that of PE-LD.
Typical application scope of PE-LD low density polyethylene: bowls, cabinets and pipe joints.
Process conditions of injection mold: drying: generally, melting temperature is not required: 180~280C ~ 280 C. Mold temperature: 20 ~ 40 C. In order to achieve uniform cooling and economic heat dissipation, it is recommended that the diameter of cooling cavity be at least 8mm, and the distance from cooling cavity to mold surface should not exceed 1.5 times the diameter of cooling cavity. Injection pressure: up to 1500 bar. Maintain pressure: up to 750 bar. Injection speed: It is recommended that the injection speed be fast. Runners and gates: Various types of runners and gates can be used. PE is especially suitable for using hot runner mold.
Chemical and physical properties: the density of commercial PE-LD material is 0.9 1~0.94 g/cm3. PE-LD is permeable to gas and water vapor. PE-LD has a high coefficient of thermal expansion and is not suitable for processing products used for a long time. If the density of PE-LD is between 0.9 1 ~ 0.925g/cm3, its shrinkage is between 2% and 5%. If the density is between 0.926 and 0.94g/cm3, the shrinkage rate is between 1.5%-4%. At present, the actual shrinkage depends on the injection molding process parameters. PE-LD can resist many solvents at room temperature, but aromatic and chlorinated hydrocarbon solvents will make it swell. Similar to PE-HD, PE-LD is prone to environmental stress cracking.
Application of polyetherimide: automobile industry (engine parts, such as temperature sensors, fuel and air processors, etc. ), electronic and electrical equipment (electrical connectors, printed circuit boards, chip housings, explosion-proof boxes, etc. ), product packaging, aircraft internal equipment, pharmaceutical industry (surgical instruments, tool housings, non-implanted instruments).
Process conditions of injection mold: drying treatment: PEI has moisture absorption characteristics, which can lead to material degradation. The required humidity value should be less than 0.02%. The recommended drying condition is 150C for 4 hours. Melting temperature: 340 ~ 400°C； for ordinary materials; The reinforced material is 340~4 15C. Mold temperature: 107~ 175C, and the recommended mold temperature is 140C. Injection pressure: 700~ 1500bar. Injection speed: Use the highest possible injection speed.
Chemical and physical properties: PEI has strong high-temperature stability, and even non-reinforced PEI still has good toughness and strength. Therefore, PEI's superior thermal stability can be used to make high-temperature heat-resistant devices. PEI also has good flame retardancy, chemical resistance and electrical insulation. The glass transition temperature is very high, reaching 2 15C. PEI also has very low shrinkage (generally 0.4%-0.7%) and good isotropic mechanical properties.
Typical application: automobile (dashboard, tool door, wheel cover, mirror box, etc. ), refrigerators, high-strength tools (hair dryers, mixers, food processors, lawn mowers, etc. ), telephone shell, typewriter keyboard, golf cart, jet ski and other entertainment vehicles.
Process conditions of injection mold: drying treatment: ABS material has hygroscopicity. It is recommended to dry at 80~90C for at least 2 hours before processing. The material temperature should be lower than 0. 1%. Melting temperature: 210 ~ 280 c; Suggested temperature: 245 degrees Celsius. Mold temperature: 25…70 degrees Celsius. Mold temperature will affect the finish of plastic parts, and low temperature will lead to low finish. Injection pressure: 500~ 1000bar. Injection speed: medium and high speed.
ABS is synthesized from acrylonitrile, butadiene and styrene. Each monomer has different characteristics: acrylonitrile has high strength, thermal stability and chemical stability; Butadiene has toughness and impact resistance; Styrene has the advantages of easy processing, high smoothness and high strength. Morphologically, ABS is an amorphous material. The polymerization of monomers in the third part produces a ternary polymer with two phases, one is the continuous phase of styrene-acrylonitrile,
The other is the dispersed phase of polybutadiene rubber. The characteristics of ABS mainly depend on the ratio of the three monomers and the molecular structure in the two phases. In this way, there is great flexibility in product design, so that hundreds of ABS materials with different qualities can be produced in the market. These different quality materials provide different characteristics, such as moderate to high impact resistance, low to high finish and high temperature deformation. ABS material has super machinability, appearance characteristics, low creep, excellent dimensional stability and high impact strength.
PA6 polyamide 6 or nylon 6
Typical application: Because of its good mechanical strength and stiffness, it is widely used in structural parts. It has good wear resistance and is also used to manufacture bearings.
Process conditions of injection mold: drying treatment: PA6 is easy to absorb moisture, so special attention should be paid to drying before processing. If the material is provided in waterproof packaging, the container should be kept sealed. If the humidity is greater than 0.2%, it is recommended to dry in hot air above 80C 16 hours. If the material is exposed to air for more than 8 hours, it is recommended to vacuum dry it at 105℃ for more than 8 hours. Melting temperature: 230 ~ 280℃, and strengthened varieties are 250 ~ 280℃. Mold temperature: 80~90C. Mold temperature will significantly affect the crystallinity, and then affect the mechanical properties of plastic parts. Crystallinity is very important for structural parts, so it is recommended that the mold temperature be 80 ~ 90℃, and for thin-walled plastic parts with long process, it is also recommended to adopt higher mold temperature. Increasing the mold temperature can improve the strength and stiffness of plastic parts, but it will reduce the toughness. If the wall thickness is greater than 3mm, it is recommended to use a low-temperature mold at 20 ~ 40℃, and for FRP materials, the mold temperature should be greater than 80℃. Injection pressure: generally between 750~ 1250bar (depending on materials and product design). Injection speed: high speed (slightly lower for reinforcing materials).
Runner and gate: Because the solidification time of PA6 is very short, the location of gate is very important. Gate aperture should not be less than 0.5*t (where t is the thickness of plastic parts). If a hot runner is used, the gate size should be smaller than the conventional runner, because the hot runner helps to prevent the material from solidifying prematurely. If an underwater gate is used, the minimum diameter of the gate shall be 0.75mm..
Chemical and physical properties: PA6 is similar to PA66 in chemical and physical properties, but it has a low melting point and a wide processing temperature range. Its impact resistance and solubility resistance are better than PA66, but its hygroscopicity is also stronger. Because many quality characteristics of plastic parts are affected by hygroscopicity, this point should be fully considered when using PA6 to design products. In order to improve the mechanical properties of PA6, various modifiers are often added. Glass is the most common additive, and sometimes synthetic rubber, such as EPDM and SBR, is added to improve the impact resistance. For products without additives, the shrinkage of PA6 is between 65438 0% and 65438 0.5%. Adding glass fiber additive can reduce the shrinkage to 0.3%~0.5% (but slightly higher in the direction perpendicular to the process). The shrinkage of molded components is mainly affected by the crystallinity and hygroscopicity of materials. The actual shrinkage is also a function of plastic parts design, wall thickness and other process parameters.
Typical application range of PA66 polyamide 66 or nylon 66: Compared with PA6, PA66 is more widely used in automobile industry, instrument housing and other products that need impact resistance and high strength requirements.
Injection mold process conditions: drying treatment: if the material is sealed before processing, it does not need to be dried. However, if the storage container is opened, it is recommended to dry it in hot air at 85 C. If the humidity is greater than 0.2%, vacuum drying at 105C and 12h is required. Melting temperature: 260 ~ 290℃. The product of glass additive is 275 ~ 280℃. The melting temperature should be avoided to be higher than 300℃. The recommended mold temperature is 80℃. Mold temperature will affect the crystallinity, and the crystallinity will affect the physical properties of the product. For thin-walled plastic parts, if the mold temperature is lower than 40C, the crystallinity of plastic parts will change with time. In order to maintain the geometric stability of plastic parts, annealing is needed. Injection pressure: usually 750~ 1250bar, depending on the material and product design. Injection speed: high speed (slightly lower for reinforcing materials). Runner and gate: Because the solidification time of PA66 is very short, the location of gate is very important. Gate aperture should not be less than 0.5*t (where t is the thickness of plastic parts). If a hot runner is used, the gate size should be smaller than the conventional runner, because the hot runner helps to prevent the material from solidifying prematurely. If an underwater gate is used, the minimum diameter of the gate shall be 0.75mm..
Chemical and physical properties: PA66 has a high melting point in polyamide materials. It is a semi-crystalline material. PA66 can maintain strong strength and rigidity at higher temperature. PA66 still has hygroscopicity after molding, and its degree mainly depends on the composition, wall thickness and environmental conditions of the material. In product design, the influence of hygroscopicity on geometric stability must be considered. In order to improve the mechanical properties of PA66, various modifiers are often added. Glass is the most common additive, and sometimes synthetic rubber, such as EPDM and SBR, is added to improve the impact resistance. PA66 has low viscosity, so it has good fluidity (but not as good as PA6). This feature can be used to process very thin components. Its viscosity is sensitive to temperature changes. The shrinkage of PA66 is between 1% ~ 2%, and the shrinkage can be reduced to 0.2%~ 1% by adding glass fiber additives. Shrinkage varies greatly in the flow direction and the direction perpendicular to the flow direction. PA66 is insoluble in many solvents, but weak to acids and other chlorinating agents.
Typical applications of PBT polybutylene terephthalate include household appliances (food processing blades, vacuum cleaner parts, electric fans, blower housings, coffee utensils, etc. ), electrical components (switch, motor housing, fuse box, computer keyboard keys, etc. ), as well as the automobile industry (radiator grille, body panel, wheel cover, door and window components, etc. ).
Process conditions of injection mold: drying treatment: this material is easy to hydrolyze at high temperature, so drying treatment before processing is very important. It is suggested that the drying condition in air is120c6 ~ 8h, or150c 2 ~ 4h. Humidity must be less than 0.03%. If it is dried by a moisture absorption dryer, the suggested conditions are 150C, 2.5 hours? Melting temperature: 225 ~ 275℃, suggested temperature: 250℃ ... Mold temperature: 40 ~ 60℃ for unreinforced materials. The cooling cavity of the mold should be well designed to reduce the bending of plastic parts. Heat loss must be rapid and uniform. It is suggested that the diameter of the mold cooling cavity is 12 mm and the injection pressure is medium (up to 1500bar). Injection speed: the injection speed should be as fast as possible (because PBT solidifies quickly). Runner and gate: circular runner is recommended to increase pressure transmission (empirical formula: runner diameter = plastic thickness+1.5mm). Various types of doors can be used. Hot runner can also be used, but attention should be paid to prevent leakage and material degradation. The gate diameter should be between 0.8~ 1.0*t, where t is the thickness of plastic parts. If it is an underwater gate, the recommended minimum diameter is 0.75mm..
Chemical and physical properties:
PBT is one of the toughest engineering thermoplastic materials. It is a semi-crystalline material with excellent chemical stability, mechanical strength, electrical insulation and thermal stability. These materials have good stability under a wide range of environmental conditions. PBT has weak hygroscopicity. The tensile strength of unreinforced PBT is 50MPa, and that of glass additive PBT is 170MPa. Too much glass additive will cause the material to become brittle. PBT crystallizes quickly, which will lead to bending deformation due to uneven cooling. For materials with glass additives, the shrinkage in the flow direction can be reduced, but the shrinkage in the vertical direction is basically the same as that in ordinary materials. The shrinkage of general materials is between 1.5%-2.8%. The shrinkage of the material containing 30% glass additive is between 0.3% and 65438 0.6%. The melting point (225%) and high-temperature deformation temperature are lower than those of PET. Vicat softening temperature is about 170℃, and glass transition temperature is between 22℃ and 43℃. Due to the high crystallization speed of PBT, its viscosity is very low, and the cycle time of plastic parts processing is generally very low.
Typical application scope of PC polycarbonate: electrical and commercial equipment (computer parts, connectors, etc. ), electrical appliances (food processors, refrigerator drawers, etc. ), transportation industry (front and rear lights of vehicles, dashboard, etc. ).
Process conditions of injection mold: drying treatment: PC material has hygroscopicity, and drying before processing is very important. The recommended drying conditions are 100C to 200C, and the drying time is 3~4 hours. The humidity before processing must be less than 0.02%. Melting temperature: 260 ~ 340 degrees Celsius. Mold temperature: 70 ~ 120℃. Injection pressure: Use as high an injection pressure as possible. Injection speed: use low-speed injection for smaller gates and high-speed injection for other types of gates.
Chemical and physical properties: PC is an amorphous engineering material with excellent impact strength, thermal stability, luster, bacteriostasis, flame retardancy and pollution resistance. The notched impact strength of PC is very high, and the shrinkage rate is very low, generally 0. 1%~0.2%. PC has good mechanical properties, but poor fluidity, so the injection molding process of this material is difficult. When choosing what quality PC material, we should take the final expectation of the product as the benchmark. If plastic parts require high impact resistance, then use PC materials with low flow rate; On the contrary, PC material with high fluidity can be used, which can optimize the injection molding process.
Chemical and physical properties: PC is an amorphous engineering material with excellent impact strength, thermal stability, luster, bacteriostasis, flame retardancy and pollution resistance. The notched impact strength of PC is very high, and the shrinkage rate is very low, generally 0. 1%~0.2%. PC has good mechanical properties, but poor fluidity, so the injection molding process of this material is difficult. When choosing what quality PC material, we should take the final expectation of the product as the benchmark. If plastic parts require high impact resistance, then use PC materials with low flow rate; On the contrary, PC material with high fluidity can be used, which can optimize the injection molding process.
Typical application scope of PET polyethylene terephthalate: automobile industry (structural devices such as mirror boxes, electrical components such as headlight mirrors, etc. ), as well as electrical components (motor housing, electrical connectors, relays, switches, microwave oven internal equipment). Industrial applications (pump housing, hand-operated instruments, etc.). ).
Process conditions of injection mold: drying treatment: drying treatment before processing is necessary because PET has strong hygroscopicity. The recommended drying conditions are 120 ~ 165℃ for 4 hours. Humidity should be less than 0.02%. Melting temperature: for unfilled type: 265 ~ 280°C；; Glass-filled type: 275 ~ 290 degrees Celsius. Mold temperature: 80 ~ 120℃. Injection pressure: 300~ 1300bar. Injection speed: Higher injection speed can be used without embrittlement. Runner and Gate: All traditional types of gates can be used. The gate size should be 50~ 100% of the thickness of plastic parts.
Chemical and physical properties: the glass transition temperature of PET is about 165C, and the crystallization temperature range of the material is 120~220C. PET has strong hygroscopicity at high temperature. For glass fiber reinforced PET materials, bending deformation is very easy to occur at high temperature. Adding crystallization enhancer can improve the crystallinity of the material. Transparent products processed with PET have glossiness and thermal deformation temperature. Special additives, such as mica, can be added to PET to minimize bending deformation. If a lower mold temperature is used, transparent products can also be obtained by using unfilled PET materials.
Typical applications of PMMA and PMMA are: automobile industry (signal lamp equipment, dashboard, etc. ), pharmaceutical industry (blood storage containers, etc. ), industrial applications (DVD, light diffuser), daily consumer goods (beverage cups, stationery, etc.). ).
Process conditions of injection mold: drying treatment: PMMA has hygroscopicity, so drying treatment before processing is necessary. The recommended drying conditions are 90C and 2~4 hours. Melting temperature: 240 ~ 270 degrees Celsius. Mold temperature: 35 ~ 70 degrees Celsius. Injection speed: medium
Chemical and physical properties: PMMA has excellent optical properties and weather resistance. The penetration rate of white light is as high as 92%. PMMA products have very low birefringence and are especially suitable for making DVD. PMMA has creep characteristics at room temperature. With the increase of load and time, stress cracking will occur. PMMA has good impact resistance. The shrinkage rate is about 0.5%.
Typical application range of POM polyoxymethylene: POM has extremely low friction coefficient and good geometric stability, and is especially suitable for manufacturing gears and bearings. Because it also has high temperature resistance, it is also used in pipeline devices (valves, pump shells), lawn equipment and so on.
Injection molding process conditions: drying treatment: if the material is stored in a dry environment, drying treatment is usually not needed. Melting temperature: homopolymer material is190 ~ 230 c; * * * The polymer material is 190~2 10C. Mold temperature: 80 ~105 c In order to reduce the shrinkage after molding, a higher mold temperature can be selected. Injection pressure: 700~ 1200bar. Injection speed: medium or high injection speed. Runner and Gate: Any type of gate can be used. If tunnel doors are used, it is better to use a shorter type. For homopolymer materials, it is recommended to use hot nozzle flow channels. For * * * polymer materials, both internal hot runner and external hot runner are acceptable.
Chemical and physical properties: POM is a tough and elastic material with good creep resistance, geometric stability and impact resistance even at low temperature. POM has both homopolymer materials and * * * polymer materials. Homopolymer material has good ductility and fatigue strength, but it is not easy to process. * * * Polymer materials have good thermal stability, chemical stability and processability. Homopolymer materials and * * * polymer materials are crystalline materials, which are not easy to absorb water. The high crystallinity of POM leads to its high shrinkage, which can reach 2%~3.5%. Different reinforcing materials have different shrinkage rates.
Typical application scope of PP and PP: automobile industry (mainly using PP with metal additives: fenders, ventilation pipes, fans, etc. ), instruments (dishwasher door gasket, dryer ventilation pipe, washing machine frame and cover, refrigerator door gasket, etc. ), daily consumer goods (lawn and gardening equipment such as lawn mower, sprinkler, etc. ).
Process conditions of injection mold: drying treatment: if stored properly, drying treatment is not needed. Melting temperature: 220~275C, be careful not to exceed 275C. Mold temperature: 40~80C, 50C recommended. The crystallinity is mainly determined by the mold temperature. Injection pressure: up to 1800 bar. Injection speed: Generally, high-speed injection molding can minimize the internal pressure. If the product surface is defective, low-speed injection molding at higher temperature should be adopted. Runner and gate: For cold runner, the typical runner diameter is 4 ~ 7 mm. It is recommended to use circular injection port and runner. All types of gates can be used. Typical gate diameters range from 1 to 1.5 mm, but gates as small as 0.7 mm can also be used. For the side gate, the minimum gate depth should be half of the wall thickness; The minimum gate width should be at least twice the wall thickness. PP material can completely use hot runner system.
Chemical and Physical Properties: Polypropylene is a semi-crystalline material. It is harder and has a higher melting point than PE. Because homopolymer PP is very brittle when the temperature is higher than 0C, many commercial PP materials are random polymers with ethylene content of 1~4% or pincer polymers with higher ethylene content. * * * Polymer-based PP material has low thermal deformation temperature (100C), low transparency, low gloss and low rigidity, but strong impact strength. The strength of polypropylene increases with the increase of ethylene content. The Vicat softening temperature of PP is150 C. Because of its high crystallinity, this material has good surface hardness and scratch resistance. PP has no problem of environmental stress cracking, and it is usually modified by adding glass fiber, metal additives or thermoplastic rubber. The range of MFR of PP is 1~40. PP with low MFR has better impact resistance, but lower tensile strength. For materials with the same MFR, the strength of polymer type is higher than that of homopolymer type. Due to crystallization, the shrinkage of PP is quite high, generally 1.8~2.5%. And the directional uniformity of shrinkage is much better than that of PE-HD and other materials. Adding 30% glass additive can reduce the shrinkage to 0.7%. Both homopolymer and polymer PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance and solubility resistance. But it is not resistant to aromatic hydrocarbon (such as benzene) solvents and chlorinated hydrocarbon (carbon tetrachloride) solvents. The oxidation resistance of PP at high temperature is not as good as that of PE.
Typical application scope of PPE polypropylene: household appliances, dishwashers, washing machines and other electrical equipment such as controller housings and optical fiber connectors.
Process conditions of injection mold: drying treatment: it is recommended to dry at 100C for 2~4 hours before processing. Melting temperature: 240~320C. Mold temperature: 60 ~ 105℃. Injection pressure: 600 ~ 1500 bar. Runner and Gate: All types of gates can be used. Especially suitable for manual gate and sector gate.
Chemical and physical characteristics: Generally speaking, the PPE or PPO materials provided in the business are generally mixed with other thermoplastic materials such as PS and PA. These mixed materials are still commonly called PPE or PPO. Mixed PPE or PPO has much better processing characteristics than pure materials. The change of characteristics depends on the proportion of the mixture, such as PPO and PS. The mixed material mixed with PA 66 has stronger chemical stability at high temperature. This material has almost no hygroscopicity, and its products have excellent geometric stability. The material mixed with PS is amorphous, while the material mixed with PA is crystalline. Adding glass fiber additive can reduce the shrinkage to 0.2%. This material also has excellent electrical insulating properties and low thermal expansion coefficient. Its viscosity depends on the proportion of the mixture in the material, and the increase of PPO proportion will lead to the increase of viscosity.
Typical application scope of PS polystyrene: product packaging, household utensils, trays, etc. Electrical (transparent container, light source diffuser, insulating film, etc. ).
Process conditions of injection mold: drying treatment: unless it is stored improperly, drying treatment is usually not needed. If drying is needed, the recommended drying condition is 80C for 2~3 hours. Melting temperature: 180~280C ~ 280 C for flame retardant materials, the upper limit is 250C C mold temperature: 40 ~ 50 C injection pressure: 200~600bar. Injection speed: It is recommended to use a faster injection speed. Runner and Gate: All traditional types of gates can be used.
Chemical and physical properties: Most commercial PS are transparent and amorphous materials. PS has very good geometric stability, thermal stability, light transmission characteristics, electrical insulation characteristics and very small moisture absorption tendency. Resistant to water and diluted inorganic acids, but can be corroded by strong oxidizing acids such as concentrated sulfuric acid, and can swell and deform in some organic solvents. Typical shrinkage is between 0.4 and 0.7%.
PA 12 Polyamide 12 or Nylon 12 Typical applications: water meters and other commercial equipment, cable sleeves, mechanical cams, sliding mechanisms and bearings.
Process conditions of injection mold: drying treatment: the humidity before processing should be below 0.65438 0%. If the material is stored in air, it is recommended to dry it in hot air at 85C for 4~5 hours. If the material is stored in a closed container, it can be used directly after 3 hours of temperature balance.
Melting temperature: 240 ~ 300°c；; Ordinary materials shall not exceed 3 10C, and materials with flame retardant properties shall not exceed 270C.
Mold temperature: non-reinforced material 30~40C, thin-walled or large-area member 80~90C, reinforced material 90~ 100C. Increasing temperature will increase the crystallinity of the material. Precise control of mold temperature is very important for PA 12. Injection pressure: up to 1000bar (low pressure and high melting temperature are recommended). Injection speed: high speed (better for materials with glass additives).
Runner and gate: for materials without additives, the diameter of runner should be about 3mm because of the low viscosity of the material. For reinforced materials, a large channel diameter of 5~8mm is needed. The shape of the runner should be all round. The injection port should be as short as possible. Various forms of doors can be used. Do not use small gates for large plastic parts. This is to avoid excessive pressure or shrinkage of plastic parts. The thickness of the gate is preferably equal to the thickness of the plastic part. If the submerged gate is used, it is suggested that the minimum diameter is 0.8 mm The hot runner mold is very effective, but it needs accurate temperature control to prevent the material from leaking or solidifying at the nozzle. If a hot runner is used, the gate size should be smaller than that of a cold runner.
Chemical and physical properties: PA 12 is a linear, semi-crystalline and crystalline thermoplastic material made of butadiene. Its characteristics are similar to those of PA 1 1, but its crystal structure is different. PA 12 is a good electrical insulator. Like other polyamides, it will not be affected by moisture. It has good impact mechanical and chemical stability. PA 12 has many improved varieties in plasticizing properties and reinforcing properties. Compared with PA6 and PA66, these materials have lower melting point and density and very high moisture regain. PA 12 is not resistant to strong oxidizing acids. The viscosity of PA 12 mainly depends on humidity, temperature and storage time. It has good fluidity. The shrinkage rate is between 0.5% and 2%, which mainly depends on the technological conditions such as material variety and wall thickness.
Typical application scope of PS polystyrene: product packaging, household utensils, trays, etc. Electrical (transparent container, light source diffuser, insulating film, etc. ).