Polycarbonate

Polycarbonate (PC) refers to a family of durable, high‑performance thermoplastics that contain carbonate groups in their repeating units. The most widely used variant is BPA-based polycarbonate, produced by polymerizing bisphenol A with phosgene via interfacial polymerization. An alternative route uses transesterification of bisphenol A with diphenyl carbonate, avoiding phosgene. Some non‑BPA and specialty polycarbonates also exist for particular applications.

Polycarbonate is notable for high impact resistance and optical clarity, making it both tough and transparent. It offers good heat resistance, with a relatively high glass transition temperature, as well as strong electrical insulation and dimensional stability. It can be stabilised for UV exposure, though without stabilization it may yellow or craze under prolonged sunlight. Chemical resistance is good for many substances but certain solvents and highly aggressive chemicals can attack or craze PC.

Processing and fabrication methods include melt extrusion, injection molding, extrusion blow molding, and thermoforming. Typical processing temperatures depend on grade and equipment, but PC is widely processed on standard thermoplastic machinery. The material is versatile for forming into sheets, films, fibers, and molded parts.

Common applications span eyewear lenses, safety visors, electronic enclosures, automotive and architectural glazing, greenhouses, and various medical or consumer products. Historically, polycarbonate was used for compact discs and DVDs, among other optical media.

Safety and environment: BPA exposure concerns have led to regulatory scrutiny in some regions, and many products are now marketed as BPA-free. Recycling is possible, typically coded as resin code 7, but recycling PC can be technically challenging and requires careful separation from other plastics. End‑of‑life management often favors mechanical or chemical recycling options.

History: polycarbonate was developed in the 1950s by Bayer and General Electric, with the first commercial production following in the late 1950s.