Engineering plastics and special plastics in the h

2022-09-21
  • Detail

Engineering plastics and special plastics in automotive applications

automotive plastics have many advantages that traditional materials did not have in the past, mainly in light weight, good appearance decoration effect, a variety of practical application functions, good physical and chemical properties, easy processing and molding, energy conservation, sustainable utilization and other aspects

engineering plastics

engineering plastics are also widely used in the automotive field because of their good comprehensive mechanical properties. In this paper, polyamide (PA), polymethylacrylate (PMMA), Polyoxymethylene (POM), polyamide (PU), polycarbonate (PC) are mainly introduced

polyamide, commonly known as nylon, has many types of PA in industrial use, including PA6, PA66 and PA610. PA is easy to print and dye, with excellent electrical properties; Resistant to drugs and oil corrosion. The commonness of machinery is toughness, which has high surface hardness, good tensile strength, good impact resistance, fatigue resistance, folding resistance and stress cracking resistance. The tensile and compressive strength of PA changes with temperature and moisture absorption, so water is relatively the plasticizer of PA. after adding glass fiber, its tensile and compressive strength can be increased by about 2 times, and the temperature resistance can be improved accordingly. The wear resistance of PA itself is very high, so it can work without lubrication

pa has poor acid resistance, light resistance and pollution resistance. Due to the influence of thermal expansion and water absorption, the dimensional stability of the workpiece is poor, and the shrinkage is 1-2%. Attention should be paid to the dimensional change of moisture absorption after molding. The water absorption rate is 100%, and it can absorb 8% when the relative moisture absorption is saturated. The suitable wall thickness is 2-3.5mm

injection molding performance: PA has strong and firm water absorption due to the existence of amide group. Therefore, it should be fully dried during injection molding, generally at 120 ℃ for hours; PA has small viscosity and fast flow speed. In order to prevent the nozzle from flowing, self-locking nozzle or nylon special nozzle should be used. At the same time, we should pay attention to the accuracy of the mold

scope of application: PA is mainly used to manufacture hoses (brake hoses, fuel pipes), combustion oil filters, air filters, oil filters, water pump housings, water pump impellers, fans, brake fluid tanks, power steering fluid tanks, white leaf windows, headlight housings, and safety belts in the automotive field

pmma

polymethacrylate, commonly known as plexiglass, is resistant to outdoor aging, has excellent light transmittance, and is exposed to the sun without affecting its transparency. After 240 hours of accelerated aging of light, it can still pass through 92% of the sunlight, 89% of it is still outdoors for ten years, and 78.5% of it is ultraviolet. High mechanical strength, certain cold resistance, corrosion resistance, good insulation performance, stable size, easy to form, brittle quality, easy to melt in organic solvents, insufficient surface hardness, easy to scratch and fuzz. Suitable plastic products: transparent structural parts with certain strength requirements

injection molding performance: the moisture absorption rate of PMMA is 0.3%. It must be dried before injection molding, generally at about 80 ℃ for 2-4h; During injection molding, the melt temperature should be 240-270 ℃, and the mold temperature should be controlled at 35-70 ℃

pmma is widely used in automobile lighting signs, door glasses and lamp glass covers because of its good light transmission performance

polyoxymethylene, commonly known as plastic steel, has high tensile strength, impact toughness, rigidity and fatigue strength, high creep resistance, good dimensional stability, small water absorption, small friction number, excellent friction and wear resistance, still has great rigidity in high temperature and water, and has the same chemical corrosion resistance as PA, but its price is low, resistant to repeated distortion, and has outstanding resilience. It can be used for a long time between -40 ℃ and -100 ℃. POM is vulnerable to strong acid corrosion, not resistant to high temperature and poor thermal stability. Shrinkage 5% suitable wall thickness: 1 5mm。

injection molding performance: POM has an obvious melting point. It melts at 175 ℃ and decomposes at 240 ℃. The general processing temperature is 190 ℃ - 220 ℃, and the production capacity is as high as 25000 tons. Its processing range is very narrow; POM does not absorb water, and generally does not need to be dried during injection molding, but products with high quality requirements can be dried at 60 ℃ for 1-2 hours; The temperature should not be too high, otherwise no dyed products will change color; It has poor acid resistance and cannot be dyed with acid dyes

scope of application: POM is used in automobiles to manufacture dashboard glove box accessories, various valves (drainage valves, air conditioner valves, etc.), various impellers (water pump impellers, heater impellers, oil pump wheels, etc.), various electrical switches and pinions on electrical instruments, various handles and door pins, etc

polycarbonate has outstanding impact toughness and creep resistance, good heat resistance, good cold resistance, embrittlement temperature of -100 ℃, bending strength is equivalent to nylon, and has high elongation and elastic modulus, but the fatigue strength is less than nylon 66. Low water absorption, small shrinkage and good dimensional stability. The wear resistance is equivalent to that of nylon, and it has certain corrosion resistance, but the forming conditions are high. It has good weather resistance and can be used for a long time under high temperature and high load, but it cannot be used under wet temperature. It has poor solvent resistance, stress cracking and poor fatigue strength. Shrinkage 0 7%, and the appropriate wall thickness is 5mm。 The shrinkage, mechanical strength and temperature resistance of PC can be improved by adding glass fiber. The steel will increase after long-term use at about 100 ℃, and the internal stress can be improved by annealing

injection molding performance: PC has an obvious melting point. It melts at 220 ℃ and decomposes at 350 ℃. The general processing temperature is 250 ℃ - the corresponding experimental scheme can be edited according to different standards - 320 ℃; It absorbs water, and a small amount of water can cause it to decompose at high temperature. It must be dried during injection molding. The drying temperature can be 120 ℃ for 4-5 hours; The melting viscosity of PC material is high, so a large pressure is needed for injection molding; When processing PC, if conditions permit, the mold temperature machine can be used to increase the mold temperature to reduce the residual stress of the product; The shrinkage of PC has nothing to do with the processing conditions and the wall thickness of the product. Its longitudinal and transverse shrinkage is relatively close, so it can be processed into products with high precision; Its shrinkage is 0.5%

main synthetic PC Abs: PC ABS is the blend material of PC and ABS, which is usually made by blending and supplied in the shape of pellets. If the two materials are simply mixed and injected directly, the effect is very poor and delamination will occur; The advantage of PC is rigid and tough, while the disadvantage is stress cracking and high viscosity; ABS has the advantage of good fluidity but low surface hardness; In this way, the blended material pc-abs retains the advantages of both; Pc-abs has high surface hardness, high rigidity and toughness, and high stress cracking resistance; Its mechanical properties are between the two

scope of application: PC is mainly used in the automotive field to manufacture lampshades, left and right wheel guards, instrument baffle body (pc+abs), left and right wind frame covers, middle wind frame covers (pc+abs), and rear bumper cushion

polyurethane, according to the difference between the anti mildew grade 0 (the highest level) generated by polymerization and the effective inhibition of mold AIDS, is commonly divided into hard polyurethane and soft polyurethane. Rigid polyurethane has high strength, good toughness, good heat insulation, good waterproof effect, simple molding process and high production efficiency; Soft polyurethane has good elasticity, sound absorption effect, aging resistance, chemical medium resistance, etc., and its comprehensive mechanical properties far exceed those of PVC and other materials. The polymerization of polyurethane is very convenient. It can not only be polymerized under normal temperature and pressure, but also can be directly foamed, sprayed, repaired and other construction after on-site polymerization

polyurethane foam is widely used in automotive interiors and vibration absorbing parts, such as coating materials, polyurethane rigid plastic plates, polyurethane elastomers, soft foam materials for seats, decorative parts, sofa leather, roof accessories; The most widely used are various soft and hard polyurethane foam materials, which have vibration isolation, sound insulation, noise reduction, thermal insulation; Pu can also be made into polyurethane coatings, adhesives, sealants, etc. for vehicles. Pu representative products on the car include instrument panel, rearview mirror, bumper, seat cushion, headrest, steering wheel, instrument panel anti vibration pad, pillar trim, front roof lining, window frame frame, ceiling and side roof frame decoration, door lining, sunshade, rear roof frame decoration, etc

special plastic glass fiber reinforced plastic

glass fiber reinforced plastic is based on the original pure plastic, adding glass fiber and other additives, so as to raise the application range of high materials such as controller power on problem, serial port connection problem, computer motherboard serial port burnout, controller serial port chip burnout. Generally speaking, most of the glass fiber reinforced materials are used in the structural parts of products, which is a kind of structural engineering materials; Such as PP, ABS, PA66, PA6, PC, POM

Copyright © 2011 JIN SHI