Many industries prefer vulcanised rubber over traditionally processed rubber because the former is stronger, more durable, and can handle extreme temperatures much better. Vulcanisation is a relatively new process and has existed for only a few centuries.
This blog will take you through the basics of vulcanised rubber, its history, uses, types, and other useful information that will help.
What is vulcanised rubber?
Vulcanisation is a process of hardening rubber. There are two kinds of rubbers commonly used – natural and synthetic. About 70% of all rubbers used these days are synthetic. These rubbers are created using various techniques and with different additives in rubber industries, depending on what features the final product needs to have.
In their initial stages, synthetic and natural rubbers can be very sticky and with low tensile strength and may not be useful at extreme temperatures or pressures. That’s why such rubbers go through vulcanisation to improve their beneficial properties and make them durable.
A brief history of vulcanised rubber
During the 1800s, the number of vehicles produced started slowly increasing all over the world. In really hot countries, there was one problem, though. The rubber in the tires got heated up on the road and would stick to the road and burst off after a while.
Rubber manufacturers were trying all kinds of ways to improve the life of tires, and this is when Charles Goodyear, a chemist, tried adding different chemicals to rubber and heating it to see if the physical properties changed.
It tool him a while to realize that the heating process was making beneficial changes and not the chemicals added. Over time, he created a process of adding sulfur and heating rubber to make it durable and hard.
This process was patented and was called vulcanisation. Vulcanised rubber handled high temperatures easily and was flexible, hard, and extremely durable. Right now, all rubber tires are vulcanised to improve their shelf life.
Where are vulcanised rubber used?
There are so many uses of vulcanised rubber in industries and everyday life. Some of the popular uses are mentioned below.
Did you know that about one billion tires are produced worldwide every year? Vulcanised rubber is in great demand throughout the year and will continue to be used for various purposes over the years.
Do also read our blog on rubber deterioration to understand how to prevent the failure of rubber parts.
Stages of vulcanisation
There are three basic stages in creating vulcanised rubber.
- Induction stage
- Curing stage
- Optimum stage
Induction stage – This is the first stage of creating vulcanised rubber. Here, the right rubber material is chosen, and in many cases, it is shaped before it gets heated. This is because once the rubber heats and hardens, it may be impossible to shape. This stage is also called the scorching stage. The heating happens gradually, and the cross-linking begins.
Curing stage – In this stage, the rubber gets heated to up to 400 degrees Fahrenheit. At this temperature, permanent cross-links are formed, and the vulcanised rubber slowly forms.
Optimum stage – In the optimum stage, the heating process is finished, and the rubber is let to get back to its new, finished state. Beyond the optimum stage, if the rubber remains hot and keeps changing properties, it is called the over-curing stage.
The number of crosslinks formed depends on how long the rubber was cured, the curing material used, the time given for the rubber to reach the optimum stage, and the natural properties of the type of rubber used.
The science behind vulcanised rubber
Natual rubber and SBR rubber vulcanisation
The science behind sulfur vulcanisation is based on cross-linking action. Sulfur vulcanisation is popularly applied to natural rubber and styrene-butadiene rubber (SBR). These types of rubber are first heated, and sulfur is added to them.
When the rubber is heated, some of the C-H bonds in the material are replaced by sulfur atom chains. This is called crosslinking. The more crosslinking that happens, the more changes the rubber material goes through.
Sulfur cross-linking gives the material strength, durability, and heat resistance.
Neoprene or polychloroprene is a type of rubber that also has several beneficial properties and hence is often vulcanised. The vulcanised rubber, in this case, comes with both the natural benefits of neoprene rubber and the strength of the vulcanisation process.
In this process, neoprene rubber is heated along with metal oxides like Zinc oxide, Magnesium oxide, and lead oxide.
What are the other additives added to vulcanised rubber?
Apart from the curing materials like sulfur or metal oxides, the following are other additives added to vulcanised rubber.
- Accelerators that quicken the vulcanisation properties like guanidines, xanthates, thiazoles, thiurams, and dithiocarbamates
- Anti-oxidants like phenolics, amines, and phosphites
- Coagulants like calcium chlorides and acetic acids
- Softeners, if needed
- Dyes or color pigments
- Anti-foaming agents
Benefits of vulcanised rubber
The following are some of the benefits of vulcanised rubber.
- High resistance to temperature changes
- Is not affected by heat
- Very durable and long-lasting
- Returns to original shape quickly
- Good insulator
- Resistant to oxidation and UV damage
- Resistant to abrasion
Vulcanised rubber is one of the most versatile materials ever found, and there have been so many industries benefit from it. vulcanization makes rubber stronger, more flexible, and extremely heat resistant.
Just like any other product, the way vulcanised rubber is made reflects in its quality. So make sure you pick the right manufacturer.
If you think your rubber components don’t last as long and as well as they used to, then maybe vulcanised components are what you need.
Arvico Rubber can help you choose the suitable rubber material to create components in, so their physical features can handle the internal and external factors they come in contact with. With an in-house designing team and a state-of-art manufacturing facility, we ensure the components we manufacture are precise and 100% adherent to expectations.