Difference between PC material and PP material
Polycarbonate is a thermoplastic resin containing - [ORO-CO] - in the main chain of the molecule. It can be divided into aliphatic, alicyclic and aliphatic-aromatic based on the different ester groups in the molecular structure. Among them, The value is aromatic polycarbonate, and the most important bisphenol A polycarbonate, the molecular weight is usually 3-10 million.
Polycarbonate, referred to as PC. PC is an amorphous, odorless, non-toxic, highly transparent colorless or yellowish thermoplastic engineering plastics with excellent physical and mechanical properties, especially excellent impact resistance, tensile strength, bending strength, high compressive strength; Small creep, dimensional stability; Has good heat resistance and low temperature resistance, in a wide temperature range with a stable mechanical properties, dimensional stability, electrical properties and flame retardancy, at -60 ~ 120 ℃ Under the long-term use; no obvious melting point, at 220-230 ℃ was molten state; due to the rigidity of the molecular chain, the resin melt viscosity; small water absorption, small shrinkage, high dimensional accuracy, dimensional stability, thin breathability ; Is a self-extinguishing material; light stability, but not resistant to UV light, good weather resistance; oil, acid, intolerant alkali, oxidizing acids and amines, ketones, dissolved in chlorinated hydrocarbons and aromatic solvents, Long-term in the water easily lead to hydrolysis and cracking, the disadvantage is due to poor fatigue strength, prone to stress cracking, poor solvent resistance, poor wear resistance.
PC injection molding, extrusion, molding, blow molding, thermoforming, printing, bonding, coating and machining, the most important processing method is injection molding. Before forming, it must be pre-dried. The moisture content should be less than 0.02%. The trace moisture will cause white turbidity color, silver wire and air bubbles when processed at high temperature. PC has a considerable capability of forcing high elastic deformation at room temperature. High impact toughness, it can be cold-pressed, cold-drawn, cold-rolled cold roll forming and other processing. Extruding PC molecular weight should be greater than 30,000, to use a gradient compression screw, aspect ratio of 1:18 to 24, the compression ratio of 1: 2.5, can be extrusion blow molding, injection - blow, injection - pull - blow molding High quality, high transparent bottle. A wide range of PC alloys to improve the PC melt viscosity (workability) and product stress cracking and other defects, PC and different polymers to form alloys or blends to improve the material properties. PC / ABS alloys, PC / PBT alloys, PC / PET alloys, PC / PET / elastomer blends, PC / MBS blends, PC / PTFE alloys, PC / PA alloys, There are two advantages of material properties and reduce costs, such as PC / ABS alloy, PC mainly contribute to high heat resistance, good toughness and impact strength, high strength, flame retardancy, ABS can improve formability, Apparent quality, reduce density. PC's three major areas of application are glass assembly, automotive and electronics, electrical appliances industry, followed by industrial machinery parts, CD-ROMs, packaging, computers and other office equipment, medical and health care, film, leisure and protective equipment. PC can be used as window glass, PC laminate is widely used in banks, embassies, places of detention and public areas of the protective window for aircraft cabin, lighting, industrial safety baffle and bullet-proof glass. PC board can be used for a variety of signs, such as gasoline pump dial, car dashboard, warehouse and outdoor commercial signs, point sliding indicator, PC resin for automotive camera systems, dashboard systems and interior decoration system, Front and rear fenders with car stiffeners, reflector frame, door frame cover, lever cover, spoiler, PC are used as junction boxes, sockets, plugs and bushings, gaskets, TV changers, telephone line support Cable connector, switch box, telephone switchboard, switchboard components, relay housing, PC can be used as low-load parts, for household appliances motors, vacuum cleaners, shampoo, coffee machine, toaster, power tool handle, each Gear, worm gear, bushings, guide regulations, refrigerator shelves. PC is the ideal material for disc storage media. PC bottles (containers) are transparent, light weight, good impact resistance, high temperature and corrosion resistant solution washing, as a recyclable bottle (container). PC and PC alloy can do the computer rack, shell and auxiliary machines, printer parts. Modified PC high-energy radiation sterilization, cooking and baking sterilization, can be used for blood specimens, blood oxygenators, surgical instruments, dialyzers, etc., PC helmets and helmets, protective masks, sunglasses and sports protection Eye mask. PC film is widely used in printing charts, pharmaceutical packaging, membrane commutator.
Polypropylene referred to as PP
Specific gravity: 0.9-0.91 g / cc Molding shrinkage: 1.0-2.5% Molding temperature: 160-220 ° C.
Features: non-toxic, tasteless, small degree of strength and stiffness, hardness, heat resistance are better than low-pressure polyethylene, can be used at about 100. Has good electrical properties and high frequency insulation from humidity, but low temperature Brittle, not wear-resistant, easy to aging. Suitable for the production of general machinery parts, corrosion-resistant parts and insulation parts. Common acid, alkali organic solvents almost no effect on it, can be used for utensils.
1. Crystalline material, hygroscopicity is small, prone to melt rupture, long-term contact with hot metal easy to decompose.
2. Good fluidity, but the contraction range and shrinkage value, prone to shrinkage. Dent, deformation.
3. Cooling speed, pouring system and cooling system should be slow cooling, and pay attention to control the molding temperature.When the material temperature is low temperature and high pressure easy orientation, the mold temperature is below 50 degrees, the plastic parts are not smooth, easy to produce poor welding, flow marks, More than 90 degrees prone to warping deformation
4. Plastic wall thickness to be uniform, to avoid lack of plastic, sharp corners, to prevent stress concentration.
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