RUBBER is a very unique material. Its main characteristic is elastic recoil, i.e. elasticity. You can stretch a rubber band until it reaches a length much greater than its original one without breaking it; then, when you let it go, it will immediately return to its original shape and length. In the same way, you can compress, bend or twist it, and it will return to its original shape each time once the stress is removed.
No other materials have the same degree of elasticity. For this reason, rubber materials are called “ELASTOMERS”.
Following the discovery of latex from the Hevea brasiliensis on the newly discovered continent, the real use of rubber in the industrial sector only began in the first half of the 1800’s, after the invention of the vulcanization process (the work of Charles Goodyear), which is based on the variation of the molecular structure of the raw product by means of sulfur. This process causes rubber to pass from a plastic state to an elastic one with constant properties that are independent of the ambient temperature. The advantages deriving from the new product became increasingly evident over the next fifty years. At the start of the 1900’s, studies and tests on rubber synthesis were ripe to give rise to the definition and patenting of butadiene rubber. The long list of the various known synthetic rubbers began here, and an acceleration in development occurred between the two world wars. There was simultaneously a growth in the knowledge of the contribution that other products, such as for example carbon black, could offer to the properties of vulcanized rubber. Later on, other studies were developed that were aimed at the use of rubber together with other materials: threads, woven threads, and metal materials, until reaching the definition of rubber textiles and rubber sheets.
Charles Goodyear was known to say: “THERE IS NO OTHER SUBSTANCE WHOSE CHARACTERISTICS AWAKEN SO MUCH CURIOSITY, SURPRISE AND WONDER AS THOSE OF RUBBER”… (taken from Manual of Rubber by Khairi Nagdi)
Elastomers have many other valuable characteristics: for example, most of them have a high degree of impermeability to water and air, a good resistance to abrasion, and good tensile strength. There are special types that can withstand temperatures higher than 200°C, and they are not affected by most of the more aggressive chemicals. Other special types retain their elasticity down to about -100°C.
The starting materials for the production of elastomers are NATURAL RUBBER or SYNTHETIC RUBBER. The rubber is mixed with various chemical additives and hot vulcanized; more rarely, cold vulcanization is performed.
Only following vulcanization does the rubber compound obtain its special elastic and mechanical properties, such as hardness, tensile strength and resistance to breakage upon elongation.