Originally, rubber is a natural product. It is tapped from the Brazilian Rubber Tree, the Hevea Brasiliensis. By adding soot and a variety of other substances its various properties can be improved and matched to the particular application. As the chemical industry developed, engineers were quick to attempt the synthetic production of rubber and to create compounds partly consisting of natural rubber and added chemical products. As a result a large number of different types of rubber were developed for various areas of application. These different kinds of rubber can be processed into flexible products with cross-linked stability that are able to withstand major deformation under great stress.
After the stress is removed, the product must recover to its original shape spontaneously and as completely as possible. Rubber stiffness is one hundred to ten thousand times lower than that of normal solids such as metals, stone and plastics. Jointly, these properties make rubber unique; for that reason, most rubber applications are based on these unique mechanical properties (e.g. shock absorbers). Rubber is often the material of choice because no suitable alternative material is available or because other solutions tend to be more expensive or less reliable. Rubber is an outstanding example of an engineered material; rubber products are commonly used at critical locations in constructions, machines, buildings etc.