[Chemistry Class Notes] on Carbon Black Pdf for Exam

Carbon black is a substance that is an intense black substance, which belongs to the carbon family. The carbon black structure is of a high surface-area-to-volume ratio, making it light and durable. It is obtained through the unfinished combustion process of heavy petroleums like coal tar, ethylene cracking tar, etc. 

In the form of carbon black pigment, i.e., being insoluble in water, carbon black can be used in almost all industries. We shall discuss it in detail in the subsequent sections, along with other topics like carbon black uses, properties, and structure.

What is Carbon Black?

Carbon black is a form of amorphous carbon which exists in various types, such as thermal black, furnace black, lamp black, and acetylene black. In its purest form, it exists in a very fine powder state. It exists in a paracrystalline form of carbon, i.e., it doesn’t have a lustre like that of a crystal and has varied disordered ordering of atoms. Let us see the structure in a little more detail.

Carbon Black Structure

Carbon black has a paracrystalline construction. A paracrystalline structure has a liquid crystal-like ordering, i.e., short-range and medium range. However, there exists no long-range ordering. Thus, the material is neither fully amorphous nor fully crystalline. The disordered ordering, i.e., the location of atoms in the lattice, is helpful in understanding polymers. 

Properties of Carbon Black

The properties of this amorphous carbon vary within types of carbon black.  In general, carbon blacks have the following properties:

• They exist in powder form and are odourless.

• They have a high melting and high boiling point.

• Specific gravity varies between 1.8 to 2.18

• It is insoluble in water and is hence called hydrophobic.

• It is highly combustible when it comes in contact with oxidizers like nitrates, chlorates, etc. It can form explosive mixtures in the air.

• Carbon black conductivity varies with the manufacturing process. When made under perfect conditions, it can offer high electric conductivity. 

• Particle Size: A smaller particle size ensures an intense black colour. However, the dispersion rate becomes less.

• Structure Size: An increase in structure size increases the conductivity of the carbon type. The blackness of the material degrades, and the dispersibility increases. 

Carbon Black Manufacturing Process

Carbon black is a product of burning petroleum products in an insufficient supply of air. The process is often called thermal decomposition and is used in hydrocarbons in industrial manufacturing. 

Nowadays, the Furnace Black Process is the most commonly employed procedure in the industry. In this process, the raw material petroleum oil or coal oil is partially combusted in a high heat supply via a furnace. The conditions are highly controlled to ensure quality.

Another manufacturing process is the channel process which uses partial charring of natural gas in a channel H-shaped steel.

The types of method and material used in the manufacturing process determine the properties and applicability of the carbon black obtained. 

Carbon Black Uses

• It is used in the food and packaging industry.

• Carbon Black absorbs the UV radiations. Hence it is mixed in polypropylene to prevent degradation.

• The high carbon black conductivity allows it to provide electrical conductivity to polymers.

• It is used in radar-absorbent materials to facilitate RF radiation-absorbing.

• Laser printers, toners, inks, paints also use different types of carbon black.

• They are also employed in the electronic industry. 

•  It is used as a filler in adhesives, films, plastics, and paints.

• Carbon black obtained from vegetables is used for food colouring.

• Some of the most common uses of carbon black are present in the automobile industry. The carbon black pigment is used here on tires. It acts as a reinforcer that helps to control the heat of the tire. This gives it durability and sustainability.

Fun Fact

Carbon black structure reflects little to no light, and hence it is black. Historically, it was procured after charring organic substances like bones, wood, etc. The product obtained was named after the material it was produced from. For instance, ivory black was created by combustion bones or ivory, while vine black was obtained via charing grape vines and stems. The uses of carbon black thus obtained included painting.