Polycarbonate: Properties and Applications

Polycarbonate - Complete Overview

What is Polycarbonate?

Polycarbonate (PC) is a thermoplastic polymer belonging to the class of synthetic polymers - linear polyesters of carbonic acid and dihydric phenols. It is one of the most technologically advanced and versatile polymers, actively developing both in the global and Russian markets.

The basis of polycarbonate is an ester bond with carbonic acid. The key monomers involved in its synthesis are bisphenol A and carbonic acid derivatives - most often phosgene or diphenyl carbonate. The macromolecular structure of polycarbonate is characterized by the presence of aromatic rings connected by carbonate groups (-O-CO-O-).

Polycarbonate stands out among modern materials for its combination of exceptional transparency and outstanding impact resistance. The material transmits light with virtually no distortion, comparable to glass, while possessing mechanical strength superior to many traditional materials. The impact strength of polycarbonate is 250 times higher than that of ordinary glass and almost 10 times higher than that of acrylic glass.

How is Polycarbonate Produced?

Polycarbonate is produced from bisphenol A (BPA) granules. Polycarbonate synthesis technologies are traditionally divided into two main types:

Phosgenation - involves the reaction of bisphenols with phosgene (interfacial polycondensation method). This is the classic method where polycarbonate is formed from diphenylolpropane and phosgene in the presence of bases.

Phosgene-free methods - such as transesterification of diaryl carbonates with bisphenols, which are considered more environmentally friendly. In Russia, a safe phosgene-free technology is used.

The production process begins with the preparation of the initial mixture: bisphenol A and diphenyl carbonate enter the reactor with a catalyst (potassium hydroxide). At temperatures from 160 to 275 °C and under vacuum, the polycondensation reaction takes place. The result is transparent granules - raw material for further processing.

Key Physical and Mechanical Properties

Polycarbonate is an amorphous thermoplastic and has a number of unique properties.

Density - 1.20-1.24 g/cm³.

Glass transition temperature - 140-150 °C. Polycarbonate does not have a clearly defined melting point.

Thermal properties - softening temperature 180-300 °C (depending on the production method). High heat resistance - up to 153 °C; heat-resistant grades withstand temperatures up to 160-205 °C. Decomposition temperature - 480-535 °C.

Operating temperature range - from -40 to +120 °C. The material withstands cyclic temperature fluctuations from -253 to +100 °C.

Strength - elastic modulus (Young's modulus) is 2200-2400 MPa. Tensile strength - 60-65 MPa.

Impact resistance - exceptionally high, which is the key advantage of polycarbonate.

Optical properties - polycarbonate has good optical properties and high transparency. Light transmission reaches 89%.

Electrical properties - excellent dielectric properties.

Chemical resistance - polycarbonate is resistant to most mineral acids (including high concentrations), salts, saturated hydrocarbons, and alcohols. However, it is destroyed by alkalis, amines, aldehydes, ketones, and chlorinated hydrocarbons.

Water absorption - insignificant.

Types of Polycarbonate

Depending on the structure and production method, polycarbonate is divided into several main types.

Solid polycarbonate - sheets of solid cross-section with a thickness of 1 to 15 mm, visually similar to acrylic or silicate glass. Available in transparent and colored versions. A solid sheet weighs twice as little as glass of the same size. Sheets withstand temperatures from -40 to +110 °C. In case of accidental breakage, polycarbonate does not shatter into small fragments.

Multi-wall (cellular) polycarbonate - has a 2-, 3-, or 4-layer structure with numerous stiffening ribs. Due to internal voids, the sheets are lightweight without loss of strength.

Profiled polycarbonate - used for specific construction tasks.

Applications of Polycarbonate

Thanks to its unique combination of properties, polycarbonate finds wide application in strategically important industries.

Construction - one of the key applications. Used for facade glazing, roofing, canopies, awnings, partitions, balcony and terrace glazing. Used in the construction of noise barriers on highways. Used as light-transmitting covering and glazing of various structures, for the manufacture of skylights.

Agriculture - greenhouses, hothouses, conservatories. Solid sheets are used in the construction of conservatories and winter gardens.

Automotive industry - headlights, diffusers, instrument panels. Polycarbonate is also used for glazing aircraft, boats, trains, and public transport.

Electronics and electrical engineering - housings of electrical appliances and power tools, consumer electronics, optical storage media (CD, DVD, Blu-Ray Disc).

Medicine - medical products, packaging, components subject to sterilization.

Advertising and design - light boxes, signs, protective screens.

Mechanical engineering and aviation - aviation and protective components. The material has even been used in the production of spacesuit elements.

Consumer goods - furniture, interior items, eyewear, food containers.

Major Polycarbonate Producing Countries

The global polycarbonate market is highly concentrated - the five largest producers account for about 75% of global capacity. The top 5 producing countries include the USA, Germany, China, South Korea, and Japan. China is the world's largest producer of polycarbonate.

Major manufacturers:

• Covestro AG (Germany) - one of the two largest producers in the world

• SABIC (Saudi Arabia) - the second largest producer

• Teijin Limited (Japan)

• Mitsubishi Engineering-Plastics Corporation (Japan)

• LG Chem (South Korea)

• Lotte Chemical (South Korea)

• Trinseo (USA)

The Asia-Pacific region is the largest consumer of polycarbonate - its share reaches 64%, and more than half of global capacity is concentrated in this region.

In Russia, polycarbonate is produced by SIBUR, which is the only producer and supplier of this raw material for processors in the country. The annual market growth is about 5-6%, with drivers of development being the expansion of applications in automotive, medicine, construction, and electronics.

Conclusion

Polycarbonate is one of the most versatile and in-demand engineering thermoplastics of our time. Thanks to its unique combination of transparency, impact resistance, heat resistance, and chemical resistance, it holds key positions in construction, automotive, electronics, medicine, and many other industries. The high concentration of global production and growing demand, especially in the Asia-Pacific region, confirm the importance of this material for the global economy. Understanding the specifics of production, properties, and applications helps market participants make informed purchasing decisions for this raw material.