Polymer architecture via abstraction of a hydrogen, can create a mid-chain growth site. Branching can be quantified by the branching index. An effect related to branching is chemical crosslinking - the formation of covalent bonds between chains. Crosslinking tends to increase T and increase strength and toughness. Among other applications, this process is used to strengthen rubbers in a process known as vulcanization, which is based on crosslinking by sulfur. Car tires, for example, are highly crosslinked in order to reduce the leaking of air out of the tire and to toughen their durability. Eraser rubber, on the other hand, is not
Thiokol Thiokol Thiokol (variously Thiokol Chemical Corporation, Morton-Thiokol Inc., Cordant Technologies Inc., Thiokol Propulsion, AIC Group, ATK Thiokol, ATK Launch Systems Group; finally Orbital ATK before becoming part of Northrop Grumman) was an American corporation concerned initially with rubber and related chemicals, and later with rocket and missile propulsion systems. Its name is a portmanteau of the Greek words for sulfur (θειον ""theion"") and glue (κολλα ""kolla""), an allusion to the company's initial product, Thiokol polymer. The Thiokol Chemical Company was founded in 1929. Its initial business was a range of synthetic rubber and polymer sealants. Thiokol was a major supplier