Rubber is an elastic, durable, and waterproof substance used in a variety of applications. There are two types of rubber: natural and synthetic.
Natural rubber is made from a runny, milky fluid called latex. This latex is part water and part rubber particles. Latex is produced by certain plants when they are cut into. About 200 plants worldwide produce latex – such as the common dandelion – but nearly all of natural rubber is produced from latex derived from Hevea brasiliensis, also known as the rubber tree. Natural rubber is a polymer of isoprene, meaning it is loosely connected units of isoprene that form long, tangled chains. These chains can be pulled apart and untangled easily, and they spring back to their original shape when released – the elastic property we associate with rubber products!
Synthetic rubber is artificially made. Types of synthetic rubber include neoprene, styrene butadiene (SBR), polyacrylics, polyvinyl acetate (PVA), polyvinyl chloride (PVC), and polyurethane.
The majority of rubber is synthetic. Synthetic rubber is superior to natural rubber due to its thermal stability and resistance to oils and oxidizing agents.
How is it made?
Natural rubber is made by tapping rubber trees and collecting the latex in a cup. The latex is then filtered, washed, and combined with acid to make the rubber particles coagulate, or stick together. Next, the rubber goes through the mastication process. Here, raw rubber is “chewed up” by mechanical rollers and pressed to make it softer, stickier, and easier to work with. Extra chemicals are then mixed in to amplify its unique properties (i.e. durability, elasticity, etc.).
One example of this process is vulcanization, in which sulfur is added and then the rubber is cooked to 280 degrees Fahrenheit. Vulcanization improves the elasticity, weather resistance, strength, and resilience of the rubber.
After undergoing chemical reactions, the rubber is calendared – pressed into shape by roller – or extruded – squeezed through specifically-shaped holes to make hollow tubes.
Synthetic rubber, on the other hand, is artificially made in chemical plants or labs using petroleum byproducts. For example, neoprene – a synthetic rubber – is made by combining acetylene and hydrochloric acid.
What is it for?
Rubber is used in a wide range of applications based on its unique properties. About half of the world’s rubber is dedicated to tire production. Natural rubber, being soft and stretchy, is used for pencil erasers, balloons, gloves, adhesives, paints, and more. Hard rubbers are used for roofing, waterproof liners in ponds, and rigid inflatable boats (RIBs). Because of its durability and thermal stability, rubber is commonly used as jacketing for electrical cables, fiber optic cables, and heat pipes. Other uses include seals, gaskets, hoses, belts, matting, and flooring.