PC Advanced FAQ

Special polycarbonate grades possess exceptional optical clarity, transmitting more than 90% of visible light, which is comparable to glass. It is used in special applications as explained here.

It performs well under the heat generated by LEDs and can withstand operating temperatures up to 120^°C. It can be formulated as clear, translucent, or opaque to achieve a highly uniform light distribution, which reduces harsh LED hot spots. PC is highly resistant to shattering and breakage. Thus, it offers superior protection against vandalism in outdoor settings.

In special applications, the material properties are critical for longevity and safety. Applications that require special polycarbonates include:

1. Outdoor street lighting (UV-resistant grade): Resists yellowing or brittleness, even with prolonged exposure to UV rays. E.g., street and parking lot lights.
2. High-output LED fixtures (heat-resistant grade): High-power LEDs generate intense heat, especially in enclosed fixtures. E.g., LED covers and housing.
3. Indoor diffusers (diffusing grade): Specialty polycarbonate diffusers are engineered to hide the intense “hotspots” of individual LEDs for even, comfortable light distribution. E.g., office and commercial troffer fixtures.
4. Safety and public infrastructure (high-impact grade): Polycarbonate is favored for its superior strength compared to glass. E.g., refrigerated display lighting.

• Injection molding (precision optics): Requires special machinery, high injection pressure, and mold temperature for proper filling.
• Extrusion (films and sheets): Involves drying the raw material before it is melted in an extruder at 280°C to 310°C.
• Hot embossing: It requires strict process control to manage the surface-to-volume ratio.
• Casting (specialty film): Some high-concentration polycarbonate films are cast to achieve high uniformity and reduce stress. Methylene chloride is often used to create specialized optical base plates.

The refractive index allows for thinner lenses compared to standard plastic. It is also lighter and more durable compared to standard glass.

Uncoated polycarbonate sheets generally show roughly 90% transmittance across the visible spectrum (~400 – 800nm). It is important to mention that transmission can vary slightly depending on thickness. Thicker samples sometimes show a wider range (approximately 47% to 73%).

Acrylic allows 92% light transmittance (comparable to glass) and is higher than the 88-90% allowed by polycarbonate. Therefore, acrylic is a better choice for high-definition, transparent optics or displays.

Birefringent materials split a single beam of light into two distinct rays, leading to two different refractive indices. When unstressed, polycarbonate is amorphous. However, because of its complex molecular structure, it becomes highly birefringent under residual strain compared to acrylic (PMMA).

Medical-grade polycarbonate is expected to meet strict regulatory standards. Two of such standards are ISO 10993 and USP Class VI. It can withstand multiple sterilization methods, including ethylene oxide (EtO), gamma radiation, and autoclaving (up to 143°C in some grades).

Medial-grade polycarbonate is engineered to comply with ISO 10993 standards for biocompatibility (including cytotoxicity, hemolysis, and skin irritation). It should be able to withstand different sterilization methods, which is crucial for maintaining a sterile patient environment.

Regulators require food-contact polycarbonate to have non-detectable or strictly limited BPA migration (e.g., the EU’s 0.05 mg/kg).

• Effective July 20, 2026, EU Regulation 2024/3190 prohibits the use of Bisphenol A in food contact articles, including polycarbonate.
• US FDA prohibits the use of polycarbonate resins in baby bottles, sippy cups, and other infant feeding items.
• ISO 10993-1: Crucial for medical-grade polycarbonate.
• UL94: Standards for flammability in medical electronics.

BPA is a well-known endocrine disruptor. It can interfere with and disrupt the body’s natural hormones, especially estrogen. Studies have linked BPA to reproductive issues, including reduced fertility. BPA exposure in pregnancy and young children can affect brain development and prostate gland health.

It is the preferred material because of its superior durability, transparency, and compatibility with sterilization methods. Specialized grades, such as Makrolon® Rx3440 and Apec® 2045, are engineered to resist cracking when exposed to hospital disinfectants.

The FDA authorizes polycarbonate use for repeated food contact, as long as they are pure enough for their intended use.

• The finished plastic must meet migration limits (the amount of substance that transfers from the plastic to the food).
• Any additive (stabilizers or colorants) used in the PC must be authorized for food contact under 21 CFR 170-189.
• The FDA no longer allows BPA-based polycarbonate resins in baby bottles and sippy cups (21 CFR 1580)

Polycarbonate exceeds several safety standards and is known for its exceptional impact resistance, 250 times that of glass. Key safety standards and certifications held by polycarbonate include:

• ANSI Z87.1 (High impact): High-velocity impact requirements
• OSHA 29 CFR 1910 Subpart O: This is a standard for machine guards
• MIL-PRF-31013 & MIL-DTL-43511D: Standard for ballistic-grade
• UL 94 V-O Rated: Flame-retardant rating

Polycarbonate roofing sheets can withstand heavy rain, floods, and high humidity. It doesn’t allow water to pass through it, which protects it from water damage.

Polycarbonate maintains structural integrity and impact resistance between –40°C (–40°F) and +120°C to 135°C (248°F–275°F) before showing signs of deformation or softening. PC has a high, stable heat deflection temperature (HDT) that allows it to maintain shape under heat. Polycarbonate is generally self-extinguishing, with some grades achieving a UL 94 V-0 flame rating.

It is frequently the choice material in earthquake-prone regions for roofing, windows, and skylights because it can withstand violent vibrations and impacts without shattering, which is the case with acrylic and glass. See other properties of PC that make it suitable for extreme environments here.

A premium, well-maintained PC installation can last over 25-30 years, while durable, unprotected polycarbonate may degrade within 2-5 years. UV radiation and extreme temperatures will cause yellowing, brittleness, and reduced light transmission. Proper installation and regular cleaning significantly extend the lifespan.

It operates reliably within a broad temperature range for short periods (-40°C to +120°C). It maintains strength in cold temperatures and resists deformation in high heat due to its high glass transition temperature of 147°C. This makes it ideal for harsh outdoor environments. Specialized high-temperature polycarbonate (PC-HT) grades are designed to withstand over 150°C.

Some of the ways polycarbonate is enhanced for tougher conditions are highlighted below:

• Abrasion-resistant coatings: Silicone-based hard coat is applied to significantly increase resistance to scratches and marring.
• UV protection layers: Protect the material from UV degradation. Benzotriazole-based stabilizers can be used for long-term stability in the outdoor environment.
• Glass or carbon fiber reinforcement: The addition of 5-40% fillers can improve tensile modulus, flexural strength, and creep resistance by up to 28 MPa.
• Flame retardants: Silicone-based and phosphorus-based additive agents can be added to achieve high fire-retardant standards.