Preparation and characterization of butyl/NBR vulcanizates

To obtain rubber compounds with satisfactory thermal and oil resistance properties, blends of butyl rubber (IIR) with nitrile rubber (NBR) were prepared on a laboratory open mill. Cure behaviour of the blends, physico-mechanical properties and ageing and oil resistance properties of the vulcanizates were determined. For electric insulation application, dielectric constant, dielectric loss and tan δ were measured. The results indicate that the vulcanizates of IIR/NBR blends of the ratios (70:30), (30:70) and (20:80), show superior thermal stability upon ageing, compared to individual rubbers and other blend compositions. Blending of IIR with NBR (main component) improves swelling behaviour of NBR in brake fluid and toluene. However, blending of NBR with IIR (main component) improves swelling resistance of IIR in motor oil and gasoline. Thus, the results obtained reveal effective improvement in thermal and oil resistance upon blending.