The Effect of Paraffinic Oil and Aromatic Oil on the Crosslinks and Physical Properties of Butyl Rubber

Butyl rubber (also known as isobutylene-isoprene rubber, IIR) compounds were prepared with paraffinic oil (PO) and aromatic oil (AO) to study the effect of the two kinds of processing oil on the crosslinks and physical properties of the IIR. The effect of processing oil on performance was studied by Mooney viscosity, differential scanning calorimetry (DSC), equilibrium swelling, mechanical and extraction experiments. The results showed that the Mooney viscosity of the PO blend was lower than that of the AO/IIR blend and the Tg of the PO blend was obviously lower than the pure IIR but the T-g of the AO blend had no change compared with pure IIR. In addition, according to the equilibrium swelling test, the average molecular weights between crosslinks of the vulcanizates which contained the processing oils were higher than that of pure IIR, with the average molecular weight between crosslinks of the AO blend, the highest, being 40.3% higher than that of the PO blend. The extraction experiments indicated that part of the processing oil could be extracted and the extracted part of AO was higher than that of the PO. Overall the PO was better than AO for acting as a processing oil for IIR.