Claus Wrana

Therban®: The high performance elastomer for the new millennium

Hydrogenated nitrile rubber (Therban) was introduced in the early 80s by Bayer as an oil-resistant elastomer for permanent exposure to temperatures between –25°C and 150°C. By specific modification of micro- and macrostructural features the service temperature range could be extended. The introduction of bulky side groups hinders the crystallization of methylene sequences along the polymer backbone. The inability to crystallize leads to superior dynamic-mechanical properties at low service temperatures. High temperature properties are determined by the plateau of rubber elasticity and are mainly influenced by the network density and structure of the crosslinked polymer matrix as well as by the polymer-filler interactions. The temperature dependence of the latter causes a decline in the reinforcement properties of filler and polymer matrix at elevated temperatures. Above 150°C a deterioration of the polymer network is observed for standard HNBR grades. This service temperature limit can be increased by ca. 10°C being equivalent to a doubling of the service life-time by the proper use of Therban HT.