Advances in Nitrile Rubber Technology

Abstract

Abstract Considerable advances have been made in NBR technology and still more are possible. The heat resistance of NBR has been raised so that it will with-stand 150°C in air for short periods, instead of 120°C. There is potential in the polymer backbone for still greater stability. It has been demonstrated that the ozone resistance of NBR can be improved by blending with EPDM, but the optimum blend has not yet been developed. The use of PVC to improve the ozone resistance of NBR is now much better understood. Crosslinked NBR has been developed as a non-migratory plasticizer which improves embossing characteristics of PVC and PVC-ABS blends. This, in turn, led to the production of NBR powders which may be used to speed up compounding on conventional equipment and permit rubber to be compounded in equipment generally used for fabricating plastics. Powder black masterbatches of NBR are now being evaluated in industry. Another new product form is liquid NBR, generally with reactive end groups. This is already established as an impact modifier for resins and may be a route to castable reinforced elastomers. Polymer structure modifications such as alternating 50:50 copolymers are interesting but do not appear to have found a market. Carboxylated NBR uses are growing in the wake of improvements in scorch resistance. Reprocessible vulcanizates based on amine-modified NBR have been announced, but a true thermoplastic NBR is still awaited.