The carbon black structure is unusual which characterizes its appearance. To understand it, we must first comprehend what carbon black is.
It’s a fine black powder made mostly of elemental carbon, arranged similar to graphite but with significant disorder.
Produced by the incomplete combustion or thermal decomposition of hydrocarbons like natural gas or petroleum oil, it’s unhealthy ecologically, which is why we at CFI Carbon Products propose a healthier alternative, Austin Black 325.
Carbon black is commonly used as a reinforcing filler in rubber products, as a pigment in inks and coatings, and in conductive applications due to its electrical properties.
The Carbon Black Structure
This elementally disordered structure is a mix of amorphous and crystalline constructions, i.e. it’s paracrystalline, and has a high surface area to volume ratio. The particles in the structure form aggregates through covalent bonding.
The larger the structure size, the more the dispersibility. However, the degree of blackness is reduced in this case.
It also shows great conductive properties when particle size is reduced.
Don’t Confuse Carbon black With Soot
Though they might look similar, carbon black isn’t soot. There’s an important distinction between the two.
Carbon black is produced under strict and controlled conditions to arrive at a product needed by the industry. Its production is therefore intentional. Soot, on the other hand, is undesired and isn’t useful for industrial applications.
The Carbon Black Properties
Properties can be modified during production to manufacture a product more in line with certain uses. This is due to carbon black’s chemical and physical structure making it flexible and multifaceted.
Physical Properties
Carbon black is a black, fine powder made of small spherical particles. Its high surface area is due to its tiny particle size and porous nature, which enhances its interaction with other materials. For instance, a higher surface area improves conductivity and viscosity.
The particle size typically ranges from tens to a few hundred nanometers depending on how it’s produced. Smaller particles provide better reinforcement in rubber and more effective UV protection.
Particle size also affects dispersibility and blackness when mixed with resins. The smaller the size is, the blacker it will be. However, dispersion becomes a problem due to a higher coagulation force.
Its porosity influences properties such as:
- Surface area – the higher the porosity, the higher the surface area.
- Conductivity – the degree of porosity affects charge transfer and electrical conductivity in coatings and batteries.
- Absorption – this factor is important for catalysis, filtration, and pigments.
- Reinforcement ability – low porosity increases durability and strength which is critical in polymers and rubbers.
Manufacturing processes and decisions can control porosity, making carbon black essential in different applications.
For instance, porosity increases surface area resulting in more interactions with the surrounding materials. Lower porosity makes it denser and a great reinforcing agent in rubber and plastics.
In gas and liquid filtration processes, microporous carbon black absorbs contaminants efficiently.
Chemical Properties
Predominantly made of carbon atoms, carbon black may contain small amounts of hydrogen due to the hydrocarbons used to produce it.
Other elements that could be present include oxygen due to incomplete combustion, sulfur, a byproduct of production, and ash, which is an inorganic impurity.
Its surface chemistry plays a crucial role in interaction with other materials like rubber reinforcement, coatings, and conductive materials.
Carbon black contains oxygen-containing functional groups on its surface. This affects dispersion and reactivity. For instance, carbon black will have different affinities with paint varnishes and inks depending on the amount and type of these functional groups.
The more hydroxyl groups due to oxidation treatment enhance its affinity to and dispersibility with varnishes and print inks.
The main functional groups are hydroxyl or -OH, carboxyl or -COOH, and carbonyl or C=O. These groups determine whether carbon black is hydrophilic (water-attracting) or hydrophobic (water-repelling).
Hydrophilic Carbon Black with an oxidized surface disperses better in water-based systems such as inks and paints. This improves paint wetting, rheology, performance, and dispersion. It also increases electrical resistivity.
Hydrophobic Carbon Black with minimal oxidation is ideal for oil-based dispersions in plastics and rubber.
Surface modification or functionalization can tailor carbon black for specific applications, making it more compatible with polar or nonpolar polymers or other substances.
To optimize performance for specific applications, carbon black can undergo chemical treatments such as:
- Oxidation to increase hydrophilicity for better dispersion.
- Surface grafting for improving compatibility with polymers.
- Functionalization with metal oxides to enhance catalytic activity in industrial processes.
Electrical Properties
Carbon black is electrically conductive, making it useful in batteries, coatings, and antistatic applications. It also has an excellent UV-blocking ability and is a common additive in plastics and coatings to prevent degradation.
Additionally, it provides a deep black color in inks, paints, and plastics due to its strong light absorption.
Conductive carbon black has lower surface oxygen content leading to higher electrical conductivity. This is useful for batteries and conductive coatings. Insulating carbon black with more surface oxidation has higher resistance and is used in UV stabilizers and paints.
Mechanical Properties
Carbon black acts as a reinforcing agent improving tensile strength, wear resistance, and elasticity in rubber products such as tires and conveyor belts.
Its ability to increase durability intensifies the mechanical properties of materials when blended into rubber, plastics, or coatings.
Carbon Black Uses
Carbon black is an important industry component used to make products stronger, longer lasting, and richer in color.
It’s mainly used to reinforce tire rubbers but also acts as a UV stabilizer, insulative or conductive agent, or pigment in rubber, coating, ink, plastic, and other applications.
It’s also a major component in automotive coatings, printing inks, plastics, conveyor belts, and hoses.
Carbon black’s role in lithium-ion batteries has revolutionized the way the industry works. This anode constituent makes the batteries safer, more stable, and energy-dense, thereby maximizing overall performance and longevity.
Additionally, It’s a great heat dissipator, crucial for ensuring safety and preventing overheating.
Carbon black is versatile due to its inherent properties and chemistry, making it an essential ingredient in many industrial applications. It’s available in different grades establishing its use in a variety of fields.
Safety And Health Concerns
As you can see, carbon black offers a multitude of benefits and has greatly impacted our economic progression. However, as with many discoveries, this element comes with its potential health and safety risks, especially when handled as a fine powder.
It can be breathed in, irritating the lungs and airways. Long-term exposure can lead to bronchitis and obstructive pulmonary disease. Carbon black is also a throat, nose, and eye irritant.
Animal studies by IARC (International Agency for Research on Cancer) suggest a risk of cancer with extremely high doses of carbon black produced through incomplete hydrocarbon combustion.
Pure carbon black is not inherently carcinogenic but contaminants from production processes may increase risk.
To minimize health and safety threats, strict handling guidelines must be followed:
Protective Measures
Wear protective equipment such as respirators or masks to prevent inhalation of fine particles, gloves and protective clothing to avoid prolonged skin contact, and safety goggles or face shields for eye protection.
Use Proper Ventilation
Work areas should have good ventilation or exhaust systems to reduce airborne dust. Enclosed systems can minimize exposure when handling bulk carbon black.
Follow Good Hygiene Practices
Wash hands and face after handling the irritant. Avoid eating or drinking in areas where carbon black dust is present.
Prevent Fire And Explosion Risks
Keep dust levels low to prevent accidental ignition since carbon black has a combustibility risk. Store carbon black away from open flames, sparks, and heat sources, and use grounded and bonded equipment to reduce static discharge risks.
Environmental Considerations
Airborne carbon black particles can contribute to air pollution if not properly contained. Waste disposal should follow environmental regulations to prevent contamination of soil and water.
Recycling and controlled elimination ensure that humans and the environment are not harmed.
For more details about carbon black and why we decided to switch to a cheaper alternative, Austin Black 325, get in touch with us today!
We understand how tough it is to make transitions when you’ve been using a product for a long time, but some changes are important, even necessary if we want a healthy future for us and our descendants.
