Kraton (polymer)

Kraton is the name given to a number of high performance elastomers manufactured by Kraton Polymers, and used as synthetic replacements for rubber. Kraton 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.

Kraton costs in the range of 1 USD per kilogramm and is used in rubber footwear and shoe soles as well as for hot melt adhesives and for as asphalt flexibilization, which is necessary if the asphalt is to be used to coat a surface that is below grade. Kraton is also popular with companies that manufacture knives for use in handles.

Properties of Kraton can be answered by its chemistry. Kraton is a block copolymer consisting of styrene and butadiene regions. Glass transition temperature (Tg) of butadiene is -70°C and Tg of styrene is +100°C. So, at any temperature between about -70°C and +100°C Kraton will act as an elastomer. If Kraton is heated substantially above the Tg of the styrene-derived blocks, that is, above about 100°C, the crosslinks change from rigid glassy regions to flowable melt regions and the entire material flows and therefore can be cast, molded, or extruded into any desired from. On cooling, this new form resumes its elastomeric character. This is the reason such a material is called a thermoplastic elastomer.

Kraton (chemie)