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A Complete Guide to Polycarbonate (PC)

Polycarbonate is a thermoplastic material which offers manufacturer and designers many possibilities while providing greater design freedom, enhanced aesthetics and cost reductions! The material is known for maintaining coloring and strength over time, even in stressful conditions.

Become an expert by learning some basic information about polycarbonates, what are its key features and properties, how to optimize its properties and popular applications. Also find out processing conditions for injection molding, extrusion, 3D Printing and safety of this versatile polymer.

What is Polycarbonate?


Polycarbonate (PC) is a high-performance tough, amorphous and transparent thermoplastic polymer which has an organic functional groups linked together by carbonate groups (–O–(C=O)–O–) and offers a unique combination of properties. It is used as an engineering plastics thanks to its:

  • High impact strength
  • High dimensional stability
  • Good electrical properties, amongst several others
Polycarbonate Corrugated Sheet

Some of the common applications are compact disc, safety helmets, bullet-proof glass, car headlamp lenses, baby feeding bottles, roofing and glazing etc.

The polymer shows excellent mechanical properties (Density: 1.2 – 1.22 g/cm3), maintains toughness upto 140°C and down to -20°C. The characteristics of polycarbonate are quite like those of polymethyl methacrylate (PMMA, acrylic), but polycarbonate is stronger, usable in a wider temperature range (Melting point: 155°C) but more expensive. PC shows excellent compatibility with certain polymers. Therefore, it is widely used in blends such as PC/ABS, PC/ PET, PC/PMMA…

Polycarbonate was first prepared in 1953 by Dr.H.Schnell of Bayer AG, Germany and by D.W. Fox of General Electric Company, USA.

Some of the polycarbonate suppliers include: SABIC (LEXAN™, CYCOLOY™) , RTP Company (PermaStat®), LG Chem (Lupoy®, Lupox®), Covestro (Makrolon®, Bayblend®, Makroblend®, Apec®), PolyOne (Edgetek™, LubriOne™), Trinseo (EMERGE™, CALIBRE™) and much more


» View all Polycarbonate commercial grades and suppliers in Omnexus Plastics Database


This plastic database is available to all, free of charge. You can filter down your options by property (mechanical, electrical…), applications, conversion mode and many more dimensions.


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Main Characteristics and Properties of Polycarbonate 


PC is a good material of choice in industry due to its versatile characteristics, eco-friendly processing and recyclability. They have the unique set of chemical and physical properties making them suitable over glass, PMMA, PE, etc.

  • Toughness and High Impact Strength – Polycarbonate has high strength that makes it resistant to impact and fracture and hence provides safety and comfort in application demanding high reliability & performance. They are virtually unbreakable.

  • Transmittance – PC is an extremely clear plastic and can transmit over 90% of light as good as glass. PC sheets are available in a wide range of shades which can be customized depending on the end0user application.

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    Transparency

  • Lightweight – The benefits allows provides OEMs virtually unlimited possibilities for design compared with glass. The property allows increased efficiency, makes installation process easier and reduces overall transportation costs.

  • Protection from UV Radiations – Polycarbonates can be designed to block ultraviolet radiation and provide 100% protection from the sun's harmful UV rays. 

  • Optical Nature - Thanks to its amorphous structure, PC offers excellent optical properties. Refractive index of clear polycarbonate is 1.584.

  • Chemical Resistance – Polycarbonate exhibits good chemical resistance against diluted acids, aliphatic hydrocarbons and alcohols; moderate chemical resistance against oils and greases. PC is readily attacked by diluted alkalis, aromatic and halogenated hydrocarbons. Manufacturers recommend to clean PC sheets with certain cleaning agents which do not affect its chemical nature. It is sensitive to abrasive alkaline cleaners.

  • Heat Resistance - Polycarbonates offers good heat resistance and are thermally stable upto 135°C. Further heat resistance can be improved by adding flame retardants without impacting material properties.


  • Polymer Matrix Selection for Very High Temperature Composites

  • Other Properties:
    • Good electrical insulation properties, not influenced by water or temperature
    • Good abrasion resistance
    • Resistant to repeated steam sterilization
    • More efficient than other engineering thermoplastics

Limitations of Polycarbonates 


There are also certain limitations associated with polycarbonate plastics:

  • Low fatigue endurance
  • Mechanical properties degrade after prolonged exposure to water at over 60°C
  • Attacked by hydrocarbons and bases
  • Proper drying before processing is needed
  • Yellows after long exposure to UV


Search PC Grades Based on
Their Reinforcement Method


Search PC Grades Based on Their Reinforcement Method

Use of Additives or Thermoplastic Blends for Optimized Properties 


Polycarbonates’ creep resistance can be further improved with addition of glass- or carbon-fiber reinforcements. 5-40% of GF reinforcements can improve creep resistance upto 28 MPa at temperature as high as 210°F. Reinforced grades have better tensile modulus, flexural- & tensile strength as compared to standard PC grades.

Additives are also added to improve flame retardancy, thermal stability, UV light and color stability and several other properties. Coated polycarbonates sheets also show better weatherability, mar and chemical resistance.

  • Stabilizers based on benzotriazole are useful for stabilization of PC against UV light and protects from UV degradation.
  • Phosphorous acid esters-based stabilizers are known to be effective in improving thermal stability of polycarbonate
  • Several flame retardants (halogenated, phosphorous-based, silicone-based) are widely used to achieve necessary UL performance, increase LOI and reduce the heat of combustion for PC products

Polycarbonate blends are successful commercially for providing right balance between performance and productivity.

PC/Polyester Blends: These alloys are suitable for applications where high chemical resistance is required. PC/PBT Blends offer higher chemical resistance than PC/PET Blends due to PBT’s higher crystalline behavior. While PET blended grades offer superior heat resistance.

PC/ABS Blends: PC’s toughness and high heat resistance combined with ABS ductility and processability provide an excellent combination of properties.


Applications of PC


As discussed above, these characteristics provide design freedom to product designers, engineers and OEMs and make polycarbonates an ideal material for use in several applications such as:

Application Description
Appliances Appliances:

Polycarbonates and its blends are used in appliances such as refrigerators, air conditioners, coffee machines, food mixers, washing machines, hair dryers steam iron water tanks etc. because they offer shape freedom through a wide range of mechanical properties. It also enhances robustness and visual appeal of product.

Automotive Automotive/Transportation:

Being lightweight and transparent, PC is used to make eye-catching design as well as enhance vehicle efficiency by reducing weight without affecting durability & improve aerodynamics of vehicle. Thanks to its high heat resistance it is used in light housing, headlamp bezel & lenses. PC blends are used in car interior and exterior body parts as well due to their rigidity and excellent creep resistance.

Building & Construction Building & Construction:

PC is known as a suitable alternative to glass in a number of glazing applications such as agricultural houses, industry or public building, facades, security windows, shelters and skylights due to the high impact strength, transparency, resistance to UV light and weatherability.

Consumer Products Consumer Products:

PC has very low birefringence, internal stress and due to its high dimensional accuracy, it is used to manufacture CDs/DVDs. Also, its high transparency allows to design innovative products for everyday life such as safety goggles, ophthalmic lenses, large-volume water bottles, etc. It’s also optically clear, which makes it ideal for things like shatterproof sunglasses, face shields, protective glasses or even as a component in bullet-proof windows.

Electrical & Electronics Electrical & Electronics:

In E&E market, PC is used in many applications such as circuit breakers, electrical housing, lighting applications, domestic switches, plug & sockets, switchgears, relays, connectors, EVs, battery packaging material, etc. The strength of polycarbonate helps prevent the housing units from breaking and polycarbonate films help prevent scratches on the screens.

Medical Medical:

Polycarbonates are majorly used in medical applications, thanks to the excellent combination of properties such as clarity, heat resistance, dimensional stability and toughness. PC can be sterilized by ethylene oxide, high energy radiation and limited autoclave cycles. Typical medical applications include surgical instruments, drug delivery systems, hemodialysis membranes, blood reservoirs, blood filters etc. where polycarbonates have been able to replace glass and metal.

Food Contact Food Contact:

Because of its heat resistance and shatter resistance, polycarbonate is used in applications for direct contact with foods and beverages. Food storage containers made from PC are reusable, help preserve freshness, protect foods from contamination and can be conveniently used in the refrigerator and microwave.

Helmets Other applications include:
  • Telecom- Mobile phone housings, pager parts
  • Urban equipment - Street lamp covers, anti- vandal glazing, food processors
  • Sports-Ski clamp parts, helmets, protective eye visors to protect children and athletes from injuries



How PC is Manufactured? 


Polycarbonates are manufactured by condensation polymerization of bisphenol A (BPA; C15H16O2) and phosgene (COCl2).


Structure of BPA Plus Structure of Phosgene Arrow Structure of Polycarbonate

Methods Used to Product Polycarbonate Parts


Polycarbonate can be processed by extrusion, injection molding, blow molding, thermoforming etc.

It is melted and forced into a mold with high pressure to give it the desired shape. Drying before processing is highly recommended: 2-4 hr at 120°C. Target moisture content should be a maximum of 0.02%.

In order to avoid material degradation, the ideal maximum residence time is between 6 and 12 minutes, depending on the selected melt temperature. There are two major techniques involved in polycarbonate processing: injection molding and extrusion (mentioned below).

Injection Molding 


Injection molding is most often used method to produce parts made from polycarbonates and its blends. Since polycarbonate is highly viscous, it is usually processed at high temperature to reduce its viscosity. In this process, the hot polymer melt is pressed through into a mold with high pressure. The mold when cools, gives the molten polymer its desired shape and characteristics. This process is generally used to manufacture polycarbonate bottles, plates, etc. Since polycarbonate is a poor-flowing plastic, wall thickness should not be too thin.

Certain guidelines that need to be followed while processing polycarbonate by injection molding are mentioned below:

Resin Melt Temperature, °C Mold Temperature, °C Molding Shrinkage, %
PC 280-320 80-100 0.5-0.8
High Heat PC 310-340 100-150 0.8-0.9
Filled PC 310-330 80-130 0.3-0.5
PC/ABS 240-280 70-100 0.5-0.7
PC/PBT 250-270 60-80 0.8-1.0
PC/PET 260-280 60-80 0.6-0.8
Typical Settings for Injection-Molding Various Polycarbonate Resins

Extrusion 


In this process, the polymer melt is passed through a cavity which helps in giving it the final shape. The melt when cooled attains and maintains the shape acquired. This process is used to manufacture polycarbonate sheets, profiles and long pipes. Some recommendations for processing polycarbonate with this technique are listed below:

  • Extrusion Temperature: 230-260°C
  • L/D ratio of 20-25 is recommended

3D Printing 


Polycarbonate is a strongest thermoplastic material and an interesting choice as a 3D Printing filament. It is a really strong material while still maintaining temperature resistance. Polycarbonate does not shatter like plexiglass.

  • Machine bendable at room temperature
  • Printing temperature from 260 – 300°C
  • Recommended printing bed temperature of 90°C or higher
  • Print speeds : 30mm/s is ideal, can go up to 60 or 80mm/s

Watch Today!
An Interesting Video on PC 3D Printing

Credit: Polymaker

Polycarbonate material can be bonded using several techniques including solvent bonding, adhesive bonding or mechanical fastening... Better understand the quality requirements for adhesive bonding processes according to regulatory standard DIN 2304-1.

Is Polycarbonate Safe for Use? How to Recycle PC? 


PC Recognized as Safe Plastic for Food Contact ApplicationsPolycarbonate plastic is a perfect material for baby bottles, refillable water bottles, sippy cups, and many other food and beverage containers. However, safety of PC came under scrutiny because it is made with bisphenol A (BPA) and research & government agencies worldwide continue to study the potential for low levels of BPA to migrate from polycarbonate products (material degradation in contact with water) into foods and beverages. These analyses have shown that potential human exposure to BPA from polycarbonate products in contact with foods and beverages is very low and poses no known risk to human health.

Several regulatory authorities worldwide, few to name US FDA, European Commission's Scientific Committee on Food, UK Food Standards Agency, have recognized safe use of PC for food contact applications but there are some studies as well which showed BPA to be a hazardous risk to health and hence, leading to development of “BPA-free” polycarbonate products.

All applications made for Polycarbonate plastic is 100% recyclable and identified by recycling code “7”. One of the methods are chemical recycling where scrapped PC is reacted with phenol to produce monomers which are purified for further polymerization.

Polycarbonate Recycling

Researchers are also working to develop new processes for recycling polycarbonates into another type of plastic—one that does not release bisphenol A (BPA) into the environment when it is used or dumped into a landfill.



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