ABSTRACT
Many of today’s challenging design problems involve materials such as butadiene rubber (BR), natural rubber (NR), or elastomers. Rubber materials might be most easily characterized by the stretching and relaxing of a rubber band. The resilience of rubber, the ability to recover initial dimensions after large strain, was not possible with natural latex until Charles Goodyear discovered vulcanization in 1939. Vulcanization is a chemical reaction known as cross-linking which turned liquid latex into a non-meltable solid (thermoset) . Cross-linked rubber would also allow considerable stretching with low damping; strong and stiff at full extension, it would then retract rapidly (rebound). One of the first applications was rubber-impregnated cloth, which was used to make the sailor’s “mackintosh.” Tires continue to be the largest single product of rubber although there are many, many other applications. These applications exhibit some or all of rubber’s four characteristics, viz. damping in motor mounts, rebound/resilience in golf ball cores, or simple stretching in a glove or bladder. While thermoset rubber remains dominant in rubber production, processing difficulties have led to the development and application of thermoplastic elastomers (TPEs). These materials are easier to process and are directly recyclable. While TPEs are not as rubberlike as the thermosets, they have found wide application in automotive fascia and as energy-absorbing materials.
