The three major transparent plastics are polystyrene (PS), PMMA and PC.
1, polymethylmethacrylate (PMMA)
Commonly known as plexiglass, the best optical properties of plastics.
PMMA mechanical and electrical properties in general, the coefficient of thermal expansion is 8-10 times that of inorganic glass. The coefficient of thermal expansion is 8-10 times that of inorganic glass, the long-term use temperature is only 80 degrees, high hygroscopicity, water absorption rate of 0.1%-0.4% after 24h immersion in water.
PMMA can be injection molding, extrusion and thermoforming transparent products can also be casting molding, the liquid PMMA monomer and catalyst together into the mold, at the appropriate temperature insulation and slow cooling.
2, polystyrene (PS)
With PMMA and PC together known as the three major transparent plastics. Its optical properties are worse than PMMA, but the moisture absorption rate is low, saturated water absorption ref 0.03% -0.05%. Molding optical products need to pay attention to the birefringence of PS products, easy to stress white and cracking. Products with poor impact resistance, low temperature brittleness is obvious. And PS products have poor weather resistance, long-term storage and sunlight will be yellow and cloudy.
3, polycarbonate (PC)
Transparent engineering plastics with excellent overall performance, PC optical properties are only lower than PMMA, but heat and cold, in the range of -135-120 degrees Celsius to maintain the stability of the mechanical properties. PC products, low hardness, poor abrasion resistance, birefringence is high, the viscosity of the PC solute is high, molding, water-sensitive, molding, high residual stress. Injection, extrusion and blow molding of high-quality PC transparent products have high process requirements.
Use
1, polystyrene
Polystyrene is easy to process and molding, and has the advantages of transparent, cheap, rigidity, insulation, good printability. Can be widely used in light industry market, daily decoration, lighting instructions and packaging. In the electrical is a good insulating material and thermal insulation materials, can make a variety of instruments shell, lampshade, optical and chemical instrument parts, transparent film, capacitor dielectric layer.
Can be used for powder and emulsion cosmetics. Used in powder has good compressibility, can improve the adhesion performance of powder. It gives skin luster and lubricating feeling, and is a high-level filler instead of talc and silica.
2, PMMA
PMMA has a lightweight, inexpensive, easy to mold and other advantages. Dissolved in organic solvents such as anisole, can form a good film and good dielectric properties, can be used as a dielectric layer of organic field effect tube.
It is molded by casting, injection molding, machining, thermoforming and so on. Especially injection molding, can be mass production, simple process, low cost. Therefore, its application is becoming more and more widespread, it is widely used in instrumentation parts, automotive lamps, optical lenses, transparent pipes.
3, polycarbonate
Optical lighting: used in the manufacture of large lampshades, protective glass, optical instruments, left and right eyepiece barrels, etc., but also can be widely used for transparent materials on the aircraft.
Electronic appliances: polycarbonate is an excellent E (120 ℃) level insulating materials, used in the manufacture of insulated connectors, coil frames, tube holders, insulating bushings, telephone shells and parts, battery shells of the lamps and so on.
It can also be used to make parts with high dimensional accuracy, such as optical disks, telephones, electronic computers, video recorders, telephone exchanges, signal relays and other communications equipment. Polycarbonate film is also widely used as capacitors, insulating leather bags, audio tapes, color video tapes and so on.
Mechanical equipment: used in the manufacture of a variety of gears, racks, worm gears, worm gears, bearings, cams, bolts, levers, crankshafts, ratchets, but also for some mechanical equipment shells, covers and frames and other parts.
Medical equipment: cups, cylinders and bottles for medical purposes, as well as dental instruments, drug containers and surgical instruments, and even as artificial kidneys, artificial lungs and other artificial organs.
Other aspects: used in construction as hollow rib double-wall panels, conservatory glass, etc.; used in the textile industry as textile yarn tubes, textile machine tiles, etc.; daily use for bottles, tableware, toys, models, LED lights shell and cell phone shells, etc..