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
Kraton (polymer) Kraton (polymer) Kraton is the trade name given to a number of high performance elastomers manufactured by Kraton Polymers (), and used as synthetic replacements for rubber. Kraton polymers offers many of the properties of natural rubber, such as flexibility, high traction, and sealing abilities, but with increased resistance to heat, weathering, and chemicals. It was first made by the chemical division of the Shell Oil Company in the 1950s, under the technical leadership of Norman R. Legge. Shell sold its Kraton polymers business to private equity firm Ripplewood Holdings in March 2001. Kraton polymers are styrenic block copolymer (SBC)