Dhristi JEE 2022-24

What is Polycarbonate?

Polycarbonate materials are referred to as groups of thermoplastic polymers that have a chemical structure containing the carbonate groups. Polycarbonates that are used in engineering need to be strong, tough materials, and some grades are optically transparent. They can easily be moulded, worked and thermoformed. Polycarbonates have a large number of applications due to their properties. It does not have a unique resin identification code and a monomer bisphenol which is also abbreviated as BPA and is present in many of the products that are made from polycarbonate. Before proceeding further with polycarbonates let us know a little bit about carbonates as well. 


Introduction to Carbonates

In chemistry, carbonate is characterized by the presence of carbonate ion that can be concluded as a polyatomic ion with the molecular formula of  CO32-and is known as the salt of carbonic acid (H2CO3). As the organic compound contains the carbonate group that is C(=O)(O–)2, it may also be referred to as carbonate ester. This term is also used for the description of the carbonation process which is referred to as a process in which the concentration of the carbonate and bicarbonate ions are increased in water to produce carbonated water or other aerated drinks. This is either done by passing carbon dioxide into the liquid by pressure or by mixing the carbonate or bicarbonate salt in water. 

In geology and mineralogy, the term carbonate is referred to as both carbonate minerals and carbonate rocks which are also formed from carbonated minerals that mainly comprises and is dominated by carbonate ions. In chemically precipitated sedimentary rock carbonate minerals are extremely varied and ubiquitous. The most common ones are the calcite and the calcium carbonate CaCO3 which is the main constituent of limestone. They are also considered as the main component of mollusc shells and coral skeletons whereas dolomite, Siderite or iron carbonate (FeCO3) and calcium magnesium carbonate CaMg(CO3)2 are the main iron ores. Since ancient times, potassium carbonate has been used for the purpose of cleaning as well as for preservatives. In modern times it is used for the manufacturing of glasses. It has a wide range of industrial applications such as preparing Portland cement and lime manufacturing, iron smelting and composing ceramic glaze and more.

Some of the typical physicochemical properties of polycarbonates are as follows:-


Physical and Chemical Properties

Physicochemical  Properties

Properties
Values

Chemical Formula

C15H16O2

Technical Name

Polycarbonate 

Molar Mass

272.29 g/mol

Solubility 

Insoluble

Tensile strength

70 - 80 N/mm²

Melt temperature

288-316 °C (550-600 °F)

Density

1.20 g/cm3

Notched Impact Strength

60 - 80 Kj/m²

Thermal Coefficient of expansion

65 x 10-6

Water Absorption, 24 hrs (%)

0.12

Tensile Strength (psi)

9500

Tensile Modulus (psi)

320,000

Tensile Elongation at Break (%)

60

Flexural Strength

15,000

Flexural Modulus (psi)

375,000

Compressive Strength (psi)

12,000

Hardness, Rockwell 

M70/R118

Coefficient of Linear Thermal Expansion

(x 10-5 in./in./°F)

3.9

Shrink Rate

0.6 - 0.9 % (.006 - .009 in/in)

Refractive

1.58 n20/D




Thermal and electrical Properties

Properties
Values

Glass transition temperature

147 °C (297 °F)

Heat deflection temperature

0.45 MPa: 140 °C (284 °F)

1.8 MPa: 128–138 °C (262–280 °F)

Vicat softening point at 50 N

45–150 °C (293–302 °F)[

Upper working temperature

115–130 °C (239–266 °F)

Lower working temperature

−40 °C (−40 °F)

Thermal conductivity at 230C

0.19–0.22 W/(m·K)

Thermal diffusivity at 230

0.144 mm²/s

Linear thermal expansion coefficient

65–70 × 10−6/K

Specific heat capacity

1.2–1.3 kJ/(kg·K)

Dielectric constant at 1 MHz

2.9

permittivity

2.568 × 10-11 F/m

Relative permittivity at 1 MHz

0.866

Permeability at 1 MHz

1.089

Dissipation at 1 MHz

0.01

Surface resistivity

1015 Ω/sq

Volume resistivity

1012 to 1014 Ω/sq 


Types of polycarbonate sheet

The polycarbonate sheets are thermoplastic and transparent sheets that are incredibly tough and absorb minimal moisture, making them resistant to impact damage as well as water damage. They are also chemical retardant as well as a flame retardant in nature. Thus some of the major types of polycarbonate sheets that are most widely used for industrial, commercial as well as housing purposes are given below:-

  1. Solid And Textured Polycarbonate Sheets: These sheets are generally made up of high-quality polycarbonate and have a strength that is 250 times the strength of the glass of the same thickness. This is a transparent polycarbonate sheet that is as clear as glass and allows 90% of the sunlight without letting harmful UV radiation enter through it. They possess thermal and chemical resistance and have the capability to withstand harsh weather conditions. 

  2. Corrugated Polycarbonate Sheets: Corrugated sheets are stronger as compared to their flat counterparts.  For commercial and industrial applications, warehouses along with residential houses are considered the most suitable polycarbonate sheet. The people who are concerned with environmental issues rely on this kind of sheet as it enhances daylight harvesting. They provide better insulation from heat as well as cold as compared to the glass sheets along with maintaining the optical properties for a longer period. They are also completely water-resistant. 

  3. Multiwall Polycarbonate Sheet: Multiwall polycarbonate resin ensures high impact strength with excellent transparency and is lightweight. Along with advanced heat reflection and light transmission, they come with a glazing system that provides outstanding flexibility in design.  They are also available mostly ranging from twin walls to five walled structures that vary the thermal insulation and therefore used in various applications. In order to ensure optimum illumination, they ensure the passage of a maximum of 80% and a minimum of 25% light transmission along with a lower heat transmission level. They retain their mechanical properties at temperatures between -40oC to +120oC and therefore are capable of tolerating extreme weather conditions.  They are highly energy-efficient and can save capital costs in terms of air conditioning and heating.

  4. Lexan Polycarbonate Sheet: They are required at large in industrial, commercial and residential applications for their properties. They are preferred because they offer excellent clarity with attractive aesthetic properties and high impact strength. They can be formed or designed easily. Along with ease of thermoforming or cold forming, the opaque sheets provides excellent impact performance and stiffness. Along with the wide colour variety, they offer a consistent high-quality surface and cost-effective part differentiation. They also have excellent flame-retardant properties. 


Polycarbonate Uses

Polycarbonate uses have raised in following years and some of their major applications are listed below:-

  1. Fencing and Protective Barrier: Along with being extremely durable and flexible they also extend the high impact resistance heating. These are also used for the construction of a variety of different types of fencing protective barriers and partitions as they have very high strength. In banks, grocery stores and other establishments they are commonly used as bulletproof barriers. Polycarbonates are also the material of choice that provides protective barriers in hockey arenas and ice skating fields.

  2. Storefront Windows: As it allows a lot of sunlight with an incredible UV protection capability they are also commonly used for or banks storefront windows and other public-facing businesses. Its transparency also allows the businesses in displaying their products so that the passerby can have a look at what the store has to offer. They do not overheat the interior and cause Sun damage for declaration of products.

  3. Safety Glasses: Along with sustaining a large amount of impact the polycarbonate plastics are also heat resistant, chemical resistant and flame retardant. Therefore this material is highly preferred for manufacturing high-performance safety goggles and glasses that have a wide variety of applications in science labs, construction sites, woodworking, welding, mining and many more.

  4. Building and Constructions: The polycarbonate plastic is 200 times stronger and more impact resistant than the glass of the same thickness. It is also more flexible and affordable than glass and can also be moulded and customised to fit the requirement. Therefore these days the polycarbonate plastic is used as an alternative to glass in many construction applications and buildings. For transparent walkways and skylights in buildings, polycarbonate has become the top choice because of its incredible strength, insulation capability and flexibility.

  5. Room Dividers: Another biggest advantage of polycarbonate plastic is that it is highly lightweight in nature compared to other elements such as glass. This makes it very easy for polycarbonate plastic to be transported and installed at any place wherever they are needed. Therefore many big and small room dividers polycarbonate plastic is the topmost choice. They are mostly used for dividing the office cubicles or as a sneeze guard in restaurants and grocery stores.

FAQs on Polycarbonate

1. What is the monomer of polycarbonate?

Polycarbonate is a polyester that is developed by the condensation reaction of carbonic acid HO–CO–OH and bisphenol A HO–(C6H6)–C(CH3)2–(C6H6)–OH.

2. What kind of plastic is polycarbonate?

Polycarbonate is an amorphous thermoplastic that is naturally transparent in nature.

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