PC: Engineering Polymer for High Performance

About this material

Polycarbonate (PC) is a polymer belonging to the class of thermoplastics, synthesized from the bisphenol A (BPA) monomers linked via carbonate groups (–OCOO–). There are two primary methods for its production: either through a synthetic route involving phosgene or via a transesterification reaction with diphenyl carbonate. It is petroleum-based, as it relies on the petrochemical industry for the production of BPA and phosgene.

Additives such as reinforcement fillers for increased strength, UV stabilizers, or flame retardants can be incorporated to enhance specific properties. Colorants are also added for aesthetic purposes. Blending PC with polyester increases chemical resistance, while blending PC with acrylonitrile butadiene styrene (ABS) can enhance impact resistance and processability.

In terms of processing, injection molding, extrusion, and blow molding yield materials of different characteristics. Injection molding can produce more precise parts, while extrusion can form continuous profiles like sheets or rods.

Strength

Polycarbonate is a very strong and durable material, demonstrating excellent impact resistance (about 200 times more resistant than glass), making it ideal for applications such as protective gear like helmets. However, polycarbonate is prone to scratching. As such, a coating is typically required to improve its scratch resistance and enable PC to be used in applications such as eyewear, protective shields, and automotive parts. Another attractive feature is its low density (nearly 50% lighter than glass), making it a lightweight choice for construction and automotive applications where ease of installation and handling is important.

Heat

Polycarbonate demonstrates good thermal stability within the range of –40 to 120 °C (–40 to 248 °F), better than acrylic, retaining its shape and strength in high-heat environments. It has a high glass transition temperature of 147 °C (297 °F), meaning that the material softens gradually above this point and begins to flow at a temperature of approximately 155 °C (311 °F). Polycarbonate can undergo deformation at room temperature without cracking or breaking. Its dimensional stability translates to the material being able to resist mechanical stress and temperature changes without warping or deforming.

Clarity and UV

Polycarbonate resembles glass in transparency, allowing up to 90% of visible light to pass through, thus enabling its use in applications such as windows, eyewear lenses, and optical discs where optical clarity is essential. However, it has low UV resistance, with prolonged exposure to UV radiation leading to degradation and discoloration. The use of UV stabilizers or coatings has greatly improved its UV resistance for outdoor applications. Finally, polycarbonate may become brittle after extended exposure to ionizing radiation above 25 kJ/kg.

Chemicals and water

Polycarbonate exhibits moderate chemical resistance to mild acids, alcohols, and oils. However, it is susceptible to degradation and cracking when exposed to strong acids, alkalis, and organic solvents such as acetone and benzene. Additionally, it has low moisture absorption, allowing it to retain its mechanical properties even in humid or wet conditions. Polycarbonate is also a good electrical insulator, naturally flame-retardant, and self-extinguishing, characteristics that make it an ideal material for applications in electronics, appliances, and automotive parts.

Sustainability

Studies have shown that polycarbonate can hydrolyze to bisphenol A (BPA) under conditions of high humidity and temperatures exceeding 70 °C, a process that may also occur in landfills at environmental temperatures and pH levels. Additionally, under anaerobic conditions, BPA has been shown to persist, indicating that the compound may remain in landfills and eventually reach the aquatic environment, leading to pollution. BPA is currently listed as a potentially hazardous chemical by many countries, underscoring the need for caution when disposing of polycarbonate.

History

Polycarbonates were discovered by German scientist Alfred Einhorn in the late 1890s. However, despite more than 30 years of research into this class of polymers, the project was abandoned, as it had not yielded commercial products. H. Schnell at Bayer patented the first linear polycarbonate and D. Fox at General Electric filed for a similar patent for a branched polycarbonate. Both companies were commercializing polycarbonate under the trade names of Makrolon (Bayer, 1958) and Lexan (GE Plastics, 1960). The original brownish color of polycarbonate was improved to the clear material known today.

Our range of Acrylic / Polycarbonate Bolts, Nuts, Washers, and Screws designed for strength, durability, and optical clarity. The acrylic material offers resistance to moisture.

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