Natural and synthetic rubber
Processing rubber
Both natural and synthetic rubber are processed to turn it into a usable product. The processes vary according to the intended use of the final product. Chemicals are added to the rubber to make it stable. Without this, the rubber would get brittle if it got cold or become sticky during high temperatures.
To make rubber strong and durable, it goes through a heat-treatment phase known as vulcanisation. The heat creates extra bonds or cross-links between the rubber molecules to make it stronger. In this process, rubber chemicals also play a key role by making it more durable and less energy-intensive. After vulcanisation, any imperfections are removed from the rubber and it is then shaped or moulded into the final product.
NATURAL RUBBER
Natural rubber is strong and flexible and protects against wear and tear, such as abrasion, fatigue, and exposure to water and certain chemicals. Natural rubber also adheres well to other materials, ideal for making enforced products, such as tires.
Natural rubber has a decent service temperature range, but there may be better choices for extreme heat, harsh lighting, or ozone exposure. Additionally, natural rubber is not highly resistant to fuel, oil, and other substances.
WHAT IS NATURAL RUBBER USED FOR?
Natural rubber can be found in thousands of products, from industrial components to everyday consumer items. These products may include hoses and belts, medical devices, protective gloves, and children’s toys.
The tire industry consumes a significant portion of the world’s natural rubber supply. Natural rubber is often found in high-performance vehicle tires because of its excellent tear strength, even at high temperatures caused by friction. Aircraft, heavy truck, and race car tires are often made from natural rubber.
The tire isn’t the only vehicle part that contains natural rubber. Brake pads, airbags, seals, and other automotive components also rely on rubber’s desirable properties to serve essential functions while the vehicle is in service.
WHAT ARE THE INGREDIENTS USED TO MAKE NATURAL RUBBER?
Every natural rubber product will have a slightly different composition profile based on its service environment. An essential natural rubber recipe includes:
- Latex – a milky white substance harvested from the rubber tree.
- Acids – to trigger clumping of filtered latex.
- Chemicals – for the prevulcanization process.
- Additives – such as fillers, curing agents, antidegradants, and more.
Industrial Applications of Natural Rubber
Most of today’s natural rubber supply comes from a single species of rubber tree, Hevea brasiliensis. Hevea brasiliensis is native to South America, but Hevea brasiliensis plantations can be found all over Southeast Asia. Some major companies are experimenting with making rubber from other plants, but Hevea brasiliensis remains the primary source.
How is rubber made? The first step of the natural rubber production process is harvesting. Rubber trees must be at least six years old before being tapped. Once the tree reaches maturity, a tapper peels back a carefully cut section of the tree’s bark, which disrupts the plant ducts and releases latex, a milky white substance. The latex flows along the grooves of the peeled-back panel and is collected in cups or bags. Rubber tappers then contain all the harvested latex and transport it for processing.
The freshly harvested latex is filtered and packaged into drums. At this stage, acid is added to the latex, which forms clumps. This clumpy fluid is rolled into sheets at a mill, which removes water and prepares the material for drying and smoking.
Next, the latex sheets are treated with chemicals and low, gentle heating, a process called prevulcanization. Stabilizers and other ingredients may be introduced at this stage, depending on the desired final properties of the rubber. Further heating transforms the sheets into a firm, black material that most people recognize as rubber. At this stage, the rubber can be molded, shaped, or otherwise processed into a final product.