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Unveiling the secrets of PC plastic particles - their unknown properties and uses
Unveiling the secrets of PC plastic particles - their unknown properties and uses
Polycarbonate (PC) is a tough,thermosetting resin that is colorless, transparent,heat-resistant, impact-resistant, flame-retardant (BI grade),and exhibits good mechanical properties within its normal operating temperature range. PC is an almost colorless, glassy,amorphous polymer with excellent optical properties.
I. Identification of PC
Material Combustion Identification: First, ignite high-value high-molecular-weight PC polycarbonate. The burning particles will gather together. After the flame is extinguished, the surface will easily form many fibers. When the flame touches the surface of the coated material, it will immediately wrinkle.
II. Performance of PC Material
1. Mechanical Properties: High strength, fatigue resistance, dimensional stability, and low creep (minimal change even at high temperatures).
2. Aging Resistance: High light transmittance (approximately 86%~92%), higher refractive index than transparent polymers such as acrylates, making it suitable for use as optical materials in lenses. The reinforced UL temperature index reaches 120~140°C (excellent long-term outdoor aging resistance).
3. Solvent Resistance: No stress cracking.
4. Water Stability: Easily decomposes in water at high temperatures (caution required in high temperature and high humidity environments).
5. Insulation Properties: Excellent, virtually unaffected by temperature, humidity, and frequency, suitable for most environments (maintains stable electrical properties even in humid and high-temperature conditions, making it an ideal material for manufacturing electronic and electrical components).
6. Dielectric Constant: 3.0-3.2.
7. Arc Resistance: 120s.
8. Chemical resistance: Resistant to water, organic acids, dilute inorganic acids, oxidants, salts, oils, aliphatic hydrocarbons, and alcohols at room temperature. However, it is susceptible to corrosion from alkalis, amines, ketones, esters, and aromatic hydrocarbons, and dissolves in solvents such as chloroform.
9. Molding and processability: Suitable for injection molding or extrusion using ordinary equipment.
I. Classification of PC
Materials Classification: Antistatic PC, Conductive PC, Fiber-reinforced Fire-retardant PC, UV-resistant and Weather-resistant PC, Food-grade PC, Chemical-resistant PC.
IV. Processing and Modification Applications of PC Material
Processing Performance:
1. Can be molded using injection molding, extrusion, blow molding, vacuum forming, thermoforming, etc., with injection molding, extrusion, and blow molding being the most common.
2. Melt viscosity is higher than that of general thermoplastics; temperature adjustment is usually used to improve fluidity.
3. Due to its susceptibility to hydrolysis at high temperatures, strict drying is required before molding. Low shrinkage allows for the molding of products with good precision.
Modification Applications: The purpose of modifying PC is to increase toughness, improve molding and processing performance, reduce residual deformation, and increase flame retardancy. Specific PC types that can be modified include:
1. PC/ABS: Improves flexural modulus, heat resistance, and electroplating performance.
2. PC/PET, PBT: Improves chemical resistance and solvent resistance.
3. PC/PMMA: Adding plexiglass enhances pearlescent appearance.
4. PC/PA, HIPS: Improves impact toughness and surface finish.
5. PC/HDPE improves boiling water resistance, aging resistance, and weather resistance, while LDPE shows poorer results.
6. PC can be reinforced with glass fiber or carbon fiber to improve mechanical strength. Using brominated flame retardants and antimony trioxide, flame-retardant PC can be produced. It can also be blended with polysulfone, aromatic polycarbonate, polyoxymethylene, polypropylene, and polystyrene to achieve a balance between economy and performance.
Injection Molding Conditions:
Drying Treatment: PC has a high water absorption rate, so preheating and drying are essential before processing. Pure PC should be dried at 120°C, while modified PC is generally dried at 110°C for at least 4 hours. The drying time should not exceed 10 hours. Adequate drying can generally be determined using air extrusion.
Melting Temperature: The processing temperature can be determined using air injection. The general processing temperature for PC is 270-320°C, while some modified or low molecular weight PCs require 230-270°C.
Mold Temperature: Too low a mold temperature can easily lead to stress concentration and cracking. The required mold temperature is 70°C to 110°C.
Injection Pressure: PC melt has a high viscosity, therefore requiring a higher molding pressure. When using a screw-type injection molding machine, the injection pressure is generally 70~140MPa, while for a plunger-type injection molding machine it is 100~160MPa. This can vary depending on the raw material, plastic product, mold, and injection molding machine.
Injection Speed: Faster injection speeds are commonly used for molding, such as for electrical switch components. A common progression is slow speed → fast molding.
Applications of PC (Polycarbonate) Engineering Plastics: The three main application areas for PC engineering plastics are glass assembly, the automotive industry, and the electronics and electrical appliance industry. Other applications include industrial machinery parts, optical discs, packaging, office equipment such as computers, medical and healthcare products, films, leisure and protective equipment, etc. PC can be used as window and door glass.
Optical Lighting: Used to manufacture large lampshades, protective glass, and eyepieces for optical instruments. It is also widely used as a transparent material in aircraft.
Electronics and Electrical Appliances: Polycarbonate is an excellent E (120°C) grade insulating material, used to manufacture insulating connectors, coil frames, tube sockets, insulating sleeves, telephone housings and parts, and battery casings for mining lamps.
Machinery Equipment: Used to manufacture various gears, racks, worm gears, worm shafts, bearings, cams, bolts, levers, crankshafts, ratchet wheels, and also for some mechanical equipment housings, covers, and frames.
Medical Equipment: Used for medical cups, tubes, bottles, as well as dental instruments, medicine containers, and surgical instruments. It can even be used as artificial organs such as artificial kidneys and artificial lungs.
Other applications: In construction, it is used as hollow-core double-wall panels and greenhouse glass; in the textile industry, it is used as textile yarn tubes and textile machine bearings; in daily life, it is used for baby bottles, tableware, toys, models, LED light housings, and mobile phone housings.
