Polycarbonate plastic

Polycarbonate is abbreviated as PC, which is the second largest variety of general-purpose engineering plastics. According to the specific composition, PC can be divided into three categories: aliphatic, aliphatic cyclic and aromatic aliphatic-aromatic, but the one with practical application value in engineering is aromatic PC, and the bisphenol A type PC with the largest output and the most widely used is the main one.
1. The performance of polycarbonate plastics
(1) General performance PC is a transparent, yellowish or white, hard and tough resin. When burning, it emits the smell of flowers and fruits, and it is self-extinguishing when it leaves the fire, and the flame is yellow, melting and foaming.
(2) Mechanical properties The mechanical properties of PC are very good, with the characteristics of rigidity and toughness. Its impact performance is the best among thermoplastics, which is 3 times higher than PA and POM, and close to the level of PF (phenolic resin) and UP FRP. The tensile strength and flexural strength of PC are good, and it is less affected by temperature. The creep resistance of PC is better than that of PA and POM, and the dimensional stability is good.
PC has poor resistance to stress cracking and high notch sensitivity. The wear resistance is average, worse than that of PA, POM, F4, etc., but higher than PSF, ABS, PMMA, etc., and the fatigue strength is low.
(3) Thermal performance: PC has good high and low temperature resistance, can be used in the temperature range of -130°C-130°C, thermal deflection temperature can reach 130-140°C, and is less affected by load, thermal conductivity and linear expansion coefficient are small, good flame retardancy, and belongs to self-extinguishing performance materials.
(4) Electrical properties PC is a weakly polar polymer with general insulation properties. However, its electrical properties vary little over a wide range of temperature and humidity, such as the dielectric constant and tangent of dielectric loss are almost unchanged in the range of 23-125°C.
(5) Environmental performance PC can be resistant to organic acids, dilute inorganic acids, salts, oils, aliphatic hydrocarbons and alcohols, but not chlorocarbons, dilute alkalis, bromine water, concentrated acids, amines, ketones and esters, etc., soluble in solvents such as methylene chloride, dichloroethane and cresol.
PC is not resistant to hot water above 60°C, and long-term exposure will lead to stress cracking and loss of toughness. The UV resistance of PC is not good, so it is necessary to add ultraviolet absorbers. However, it has good resistance to air and ozone.
(6) Optical performance PC is one of the most excellent optical plastic varieties, with a light transmittance of up to 93% and a refractive index of 1.587, which is suitable for lens materials. As a high-grade optical material, PC has the disadvantages of low hardness and poor wear resistance, and high birefringence, which is not suitable for high-precision products such as optical instruments.
2. Processing characteristics of polycarbonate plastics
The melt viscosity of PC is very high, up to 103-104Pa•s, and the rheology of the melt is close to that of Newtonian fluids at low shear rates, and the fluidity should be mainly regulated by temperature. Short cooling, solidification and setting times during molding.
The rigidity of PC is large, and it is easy to produce internal stress during processing, so the molding process conditions should be strictly controlled and post-processing should be carried out.
PC is extremely sensitive to water during the molding process, and trace amounts of water can also cause decomposition at high temperatures. Therefore, it must be dried before processing so that the water content is less than 0.02%.
PC is an amorphous polymer with low molding shrinkage. PC products are not easy to have metal inserts, if they must be added, the inserts should be preheated to 200°C or higher.
PC is relatively easy to process, and can be processed by injection molding, extrusion and blow molding.
3. Modified varieties of polycarbonate plastics
(1) Enhance your PC
The reinforcing materials are glass fiber, carbon fiber and boron fiber, etc., which can significantly improve fatigue strength, tensile strength, bending strength and compressive strength, improve stress crack resistance and heat resistance, and reduce water absorption, linear expansion coefficient and molding shrinkage. However, the impact strength will be reduced.
(2) PC alloy
There are many types of PC alloys, and they have been widely used.
(1) The purpose of PC/ABS is to reduce internal stress and improve processing fluidity. This alloy has been used in machinery, electrical appliances, hats and auto parts and other products.
(2) PC/HDPE can reduce melt viscosity, improve processing performance, increase impact strength, and improve stress crack resistance.
(3) PC/POM can be mixed in any proportion. When the POM is less than 25%, the mechanical properties of PC do not change much, but the solvent resistance and stress crack resistance can be significantly improved, and the heat resistance can also be significantly improved.
(4) PC/F4 can improve the wear resistance by 5 times, if glass fiber is added to it, the PV value can be greatly improved.
(5) PC/PBT(PET) alloy has good heat resistance, chemical corrosion resistance, stress crack resistance, wear resistance, low temperature impact resistance, and good molding processability. This alloy can be used in automobile bumpers and body guards.
(6) PC/PMMA alloy has the advantages of good solvent resistance, high notched impact, good heat resistance, easy processing, and ultraviolet resistance. The product has a pearl-like luster and can be used in the manufacture of ornaments.
(7) PC/PA alloy has good chemical corrosion resistance and high impact strength. It can be used for automobiles, home appliances, compact discs, etc.
4. Application range of polycarbonate plastics
(1) Optical materials: Lighting materials such as large lampshades, architectural lighting panels, window glasses, protective glass, etc., optical lens materials, laser discs and optical fiber materials, etc.
(2) Electronic/electrical PC is an E-class insulating material, injection molded parts can be used for connectors and coil frames, etc., and films can be used for capacitors, video tapes, audio tapes, etc.
(3) Mechanical parts can be used for gears, racks, worm gears, cams, tie rods, crankshafts and housings, etc.
(4) Packaging materials use its transparency and heat resistance to use the turnover barrel of purified water and mineral water, travel hot water cups, feeding bottles and tableware.
(5) Medical equipment Medical devices such as surgical instruments, dental equipment, drug containers (cups, bottles, barrels, cans), medical materials such as artificial kidneys, artificial lungs and other artificial instruments.