What is Polycarbonate(PC)
Polycarbonate also known as PC plastic material; is a polymer containing carbonate groups in the molecular chain. According to the structure of the ester group, it can be divided into aliphatic, aromatic, aliphatic-aromatic and other types. type. Among them, the low mechanical properties of aliphatic and aliphatic-aromatic polycarbonates limit their application in engineering plastics.
Only aromatic polycarbonate has achieved industrial production. Due to the special structure of polycarbonate, it has become the fastest growing general engineering plastic among the five major engineering plastics.
PC plastic chemical composition
Polycarbonate is a strong thermoplastic resin that gets its name from its internal -O-C(=O)-O- groups. It can be synthesized from bisphenol A and phosgene (COCl2). The most commonly used method is the melt transesterification method (bisphenol A and diphenyl carbonate are synthesized through transesterification and polycondensation reaction).
Chemical properties:
Polycarbonate (PC) is a polyester of carbonic acid. Carbonic acid itself is not stable, but its derivatives (such as phosgene, urea, carbonates, and carbonates) have certain stability.
According to different alcohol structures, polycarbonates can be divided into aliphatic and aromatic categories.
Aliphatic polycarbonate. For example, polyethylene carbonate, polytrimethylene carbonate and their copolymers have low melting point and glass transition temperature and poor strength, so they cannot be used as structural materials; however, they can be used as structural materials by taking advantage of their biocompatibility and biodegradability. It has been used in drug sustained release carriers, surgical sutures, bone support materials, etc.
Polycarbonate is resistant to weak acids, weak alkali and neutral oils.
Polycarbonate is not resistant to UV light or strong alkali.
PC is a linear carbonic polyester in which carbonic acid groups are alternately arranged with other groups in the molecule. These groups can be aromatic, aliphatic, or both. Bisphenol A type PC is the most important industrial product.
PC is an almost colorless glassy amorphous polymer with excellent optical properties. PC high molecular weight resin has high toughness. The notched Izod impact strength is 600~900J/m. The heat distortion temperature of unfilled grades is approximately 130°C. Glass fiber reinforcement can increase this value by 10°C. The flexural modulus of PC can reach more than 2400MPa, and the resin can be processed into large rigid products. Below 100°C, the creep rate under load is very low. PC has poor hydrolysis resistance and cannot be used in products that are repeatedly subjected to high-pressure steam.
The main performance defects of PC are insufficient hydrolysis stability, sensitivity to notches, resistance to organic chemicals, poor scratch resistance, and yellowing after long-term exposure to ultraviolet rays. Like other resins, PC is susceptible to corrosion by certain organic solvents.
PC material is flame retardant. Antioxidant properties.
Physical properties:
Density: 1.18-1.22 g/cm3 Linear expansion rate: 3.8×10-5 cm/°C Thermal deformation temperature: 135°C Low temperature -45°C
Polycarbonate is colorless and transparent, heat-resistant, impact-resistant, flame-retardant BI grade, and has good mechanical properties within normal operating temperatures. Compared with polymethyl methacrylate, which has properties close to that of polymethyl methacrylate, polycarbonate has good impact resistance, high refractive index, good processing performance, and has UL94 V-2 flame retardant properties without the need for additives. However, polymethylmethacrylate is less expensive than polycarbonate and can produce large-scale devices through bulk polymerization.
The wear resistance of materials is relative. If you compare ABS materials with PC materials, PC materials have better wear resistance. However, compared with most plastic materials, the wear resistance of polycarbonate is relatively poor, at the middle to lower level, so some polycarbonate devices used for easy-wear purposes require special surface treatment.
