Natural rubber isn't just ready to go and turned into tires immediately. It has to go through several different processes. One of them is the vulcanization process. But what is vulcanization?
Vulcanization is a form of curing. In the 1800s, Goodyear, the man not the company, was searching for a way to come up with a way to make sure that the rubber that was getting used for all kinds of things was stronger, tougher, and less sticky. His research came up with the vulcanization process, a curing process that uses heat and/or chemicals to cure the rubber to make it stronger. He decided to name his process after Vulcan, the Roman god of volcanos, among other things. But how does vulcanization work?
In rubber, just like anything else, there are chains of polymers that make it up. Those polymer chains just exist in the rubber and aren't really connected up to each other in any way. However, the various processes and chemicals that go into vulcanizing the rubber make it so that the polymers line up and cross-link together, which toughens up the rubber and cures it. Think of it like a scaffolding. By themselves, each polymer chain is like one pole of the scaffolding. But once it's gone through the vulcanization process, those pipes line up and then start linking together, just like the cross beams in the scaffolding and boards where people stand. All those things make the natural rubber much more stable and much stronger. It lets the rubber stand up to the use and abuse that it's going go through while being used in tires, electrical insulation, shoe soles, or whatever use the rubber is about to be used for.
There are several different vulcanization processes. Some products will go through just one process, others will go through a combination thereof, so that they are going to be as strong as possible. The most common processes including heating up the rubber to a certain temperature and adding in a range of chemicals. The most common chemical to be added to rubber is sulfur. It may be just straight sulfur or some derivative of sulfur.
Making strong rubber is important to setting up products that will last for years and stand up under a lot of wear and tear. Vulcanization is the way to make sure that the natural rubber is as strong as possible.