Terminology

• PC: polycarbonate
• Makrolon / Lexan: trade names (Bayer, GE)
• BPA: bisphenol A, a monomer released by hydrolysis
• LOI: limiting oxygen index
• Domelight: formed dome skylight

History and demand

Invention

• 1953: Hermann Schnell of Bayer patented the first linear polycarbonate; Daniel Fox of General Electric synthesized a branched version about a week later
• 1958: Bayer began commercial production as Makrolon; 1960: GE followed with Lexan

Sourcing

• Asia-Pacific holds an estimated 65 to 75 percent of about 8.1 million tons of global capacity; China's capacity was under 2 million tons in early 2020 and is projected near 4 million tons by the end of 2025 (market research)
• GlobalData's country ranking by capacity lists China first, then the United States, South Korea, Thailand, and Germany (2022)

Demand trend

• About one billion kilograms produced annually; construction is the second-largest consumer (domelights, glazing, roofing sheets, and sound walls)

Properties

Physical

• Density: 1.20 to 1.22 g/cm³ (about 75 to 76 lb/ft³)
• Light transmission: essentially amorphous and highly transparent, better than many glasses

Mechanical

• Tensile strength: 55 to 75 MPa (8.0 to 10.9 ksi)
• Modulus of elasticity: 2.0 to 2.4 GPa (290 to 350 ksi)
• Impact strength: Izod 600 to 850 J/m; notched Charpy 20 to 35 kJ/m²

Thermal and moisture

• Coefficient of thermal expansion: 65 to 70 × 10⁻⁶ per K, about 36 to 39 × 10⁻⁶ in./in./°F
• Glass transition: about 147°C (297°F); flow above about 155°C (311°F)

Fire behavior

• Rating: HB-V2 as given; limiting oxygen index 25 to 29 percent

Durability

• UV: fair; standard resins are unsuitable for long-term UV exposure, so UV stabilizers are often added

Standards

Test methods

• ASTM D635, D1929, D2843: burning extent, self-ignition, and smoke density (plastics classification)

Uses in buildings

Building elements

• Skylights and Roof Windows: dome and pyramid glazing
• Overhead Sectional Doors: glazing in full-view sections
• Greenhouse and Canopy Glazing: multiwall and solid sheet roofing and domelights

Pros and cons

Pros

• Izod impact strength 600 to 850 J/m
• Light transmission better than many glasses
• Lighter than glass (1.20 to 1.22 g/cm³)

Cons

• Fair UV resistance; needs stabilizers
• High thermal expansion
• Hydrolysis at high temperature releases BPA

Design considerations

Movement

• Expansion about 0.43 to 0.47 in. per 10 ft for a 100°F swing (calculated from 36 to 39 × 10⁻⁶ in./in./°F)

Sustainability

Health

• Hydrolysis at high temperature releases bisphenol A; alkali cleaners and bleach can accelerate release

Manufacturing and cost

Main manufacturers and suppliers

• Covestro
• SABIC
• Palram
• Trinseo

Trade association: American Chemistry Council.

Sources

• Wikipedia: Polycarbonate, https://en.wikipedia.org/wiki/Polycarbonate
• UpCodes: 2024 IBC Chapter 26 plastic, https://up.codes/viewer/department-of-defense/ibc-2024/chapter/26/plastic
• Wikimedia Commons: Bottom of 18.9 Liter (5 Gallon) jug made by GREIF, plastic type PC (polycarbonate).jpg, photo by Yerachmiel C (CC0), https://commons.wikimedia.org/wiki/File:Bottom_of_18.9_Liter_(5_Gallon)_jug_made_by_GREIF,_plastic_type_PC_(polycarbonate).jpg
• GlobalData: China to lead global polycarbonate capacity additions through 2030, https://www.globaldata.com/media/oil-gas/china-to-lead-global-polycarbonate-capacity-additions-through-2030-says-globaldata/
• GII Research: polycarbonate resins global market overview, https://cn.gii.tw/report/inde1207187-polycarbonate-pc-resins-global-market-overview.html