Introduction to Rubber Elastomers
The basic core polymer of elastic compounds is called rubber, which can be produced in the form of natural rubber in the wild, commercial rubber plantations, or synthesized and manufactured by the chemical industry. Today, over 32 types of synthetic rubber are known, with the most important ones listed in Table 2-1. Modern elastic sealants typically contain 50% to 60% of the base polymer, commonly referred to as “rubber”. The remaining parts of the elastomer compound are composed of various fillers, vulcanizing agents, accelerators, aging inhibitors, and other chemical additives that can modify and improve. If basic design requirements are followed, elastomers used for producing seals, especially those used for O-rings, typically provide reliable and leak free functionality. The “cross-linking” between polymer chains is formed during the vulcanization process, as shown in Figure 2-1. The cross-linking of molecules transforms rubber from a plastic like material to an elastic material. After vulcanization, including any required ‘post curing’, the elastomer compound obtains the physical properties required for a good sealing material. Like all chemical reactions, temperature determines the rate of reaction. Only by maintaining a constant ideal process temperature throughout the entire vulcanization process can the optimal degree of vulcanization be achieved.