Author: Adam Gosling, TyreSafe Australia
Mention the word ‘tyres’ and most people immediately think of rubber, but interestingly a tyre is closely related to a diamond, due to the essential role of ‘Carbon Black’ – a sophisticated cousin of soot – in tyre engineering.
Carbon is one of the most abundant elements on our globe and as a single element it comes in many different forms from lead pencils to diamonds to water filters. In chemical combination it is everywhere – hydrocarbons fuel our vehicles and make plastics. Carbon is all around us in flora and fauna – indeed a forest is otherwise known as a carbon bank.
Tyre rubber compounds contain a substantial quantity of ‘carbon black’, an extremely fine and relatively pure form of the carbon element. And without the addition of carbon black to rubber compounds the humble pneumatic tyre as we know it wouldn’t exist – rubber in its ‘natural’ state is white, soft and has poor resistance to abrasion.
So yes, carbon black is the reason that tyres are black. But there’s more to it than that. There are synthetic rubbers and natural rubbers, but carbon black is unique in its ability to enhance the critical properties of nearly any base material used in rubber manufacture – it significantly increases the stiffness, tensile strength and abrasion resistance of rubber compounds. So carbon black is critical to the strength, handling, wear and durability of any rubber tyre.
Carbon black is produced in a furnace, predominantly from petroleum, as a product of incomplete combustion. Basically, it is formed from smoke – albeit a specifically engineered smoke that requires precise processing and handling to produce the exact qualities of the carbon black required.
The particle size of carbon black used in tyre manufacturing ranges from just 10 nanometres to 500 nanometres and the dispersal of the carbon particles throughout the rubber compound is critical. So the manufacturing processes for carbon black require some very clever manipulation to ensure that exact consistency is achieved in the final rubber compounds – a small variation may mean a disaster when it is all put together as a tyre.
Tyres may be a black science, but rubber technology is truly a black art – with carbon black front and centre.