What is carbon black and why so much of it?
Carbon black is very finely powdered, very pure carbon, a bit like the soot that forms on the inside of an oil lamp.
Its very important in tire rubber. To begin with, its a filler, making up about 30 percent of the tire, which is a lot when you consider how light carbon black is.
What does a filler do?
It adds enormous strength. One way to think of rubber is to compare it to the concrete in a modern building.
Often, we embed steel bars in the concrete, adding strength. Rubber reinforced with carbon black is much more abrasion-resistant than rubber alone, is stronger, wears more slowly, and is easier to process.
Carbon black also helps protect rubber against ultraviolet (UV) light from the sun.
Why is that important?
You might say that like our skin, tires can get a sort of sunburn, which can cause rubber molecules to break down and become brittle. That can make tires wear faster and cause surface cracks.
Carbon black tends to shield rubber molecules from UV light, like a sunscreen.