Polycarbonate (PC)

Polycarbonate is a durable material. Although it has high impact-resistance, it has low scratch-resistance. Therefore, a hard coating is applied to polycarbonate eyewear lenses and polycarbonate exterior automotivecomponents. The characteristics of polycarbonate compare to those of polymethyl methacrylate (PMMA, acrylic), but polycarbonate is stronger and will hold up longer to extreme temperature. Thermally processedmaterial is usually totally amorphous,[7] and as a result is highly transparent to visible light, with better light transmission than many kinds of glass.Polycarbonate has a glass transition temperature of about 147 °C (297 °F),[8] so it softens gradually above this point and flows above about 155 °C (311 °F).[9] Tools must be held at high temperatures, generally above80 °C (176 °F) to make strain-free and stress-free products. Low molecular mass grades are easier to mold than higher grades, but their strength is lower as a result. The toughest grades have the highest molecularmass, but are more difficult to process.Unlike most thermoplastics, polycarbonate can undergo large plastic deformations without cracking or breaking. As a result, it can be processed and formed at room temperature using sheet metal techniques, such asbending on a brake. Even for sharp angle bends with a tight radius, heating may not be necessary. This makes it valuable in prototyping applications where transparent or electrically non-conductive parts are needed,which cannot be made from sheet metal. PMMA/Acrylic, which is similar in appearance to polycarbonate, is brittle and cannot be bent at room temperature.

extrusion into tubes, rods and other profiles including multiwallextrusion with cylinders (calenders) into sheets (0.5–20 mm (0.020–0.787 in)) and films (below 1 mm (0.039 in)), which can be used directly or manufactured into other shapes using thermoforming or secondaryinjection molding into ready articlesPolycarbonate may become brittle when exposed to ionizing radiation above 25 kGy (J/kg).[10

Disposal

Studies have shown that at temperatures above 70 °C, and high humidity, polycarbonate will hydrolyze to Bis-phenol A (BPA). After about 30 days at 85 °C / 96% RH, surface crystals are formed which for 70% consisted of BPA.[34] BPA is a compound that is currently onthe list of potential environmental hazardous chemicals. It is on the watch list of many countries, such as United States and Germany

-(-OC6H4)2C(CH3)2CO-)-n + H2O {\displaystyle \longrightarrow } (CH3)2C(C6H4OH)2 + CO2

The leaching of BPA from polycarbonate can also occur at environmental temperature and normal pH (in landfills).The amount of leaching increases as the discs get older. A study found that the decomposition of BPA in landfills (under anaerobic conditions)It will therefore be persistent in landfills. Eventually, it will find its way into water bodies and contribute to aquatic pollution