Determination of ethylene‐propylene rubber in crosslinked blends with 1,4‐polybutadiene

Crosslinked blends of ethylene‐propylene rubber (EPR) and 1,4‐polybutadiene (BR) were investigated by metathesis degradation of the BR component; the percentage of EPR was determined by weighing the polymeric residue. The metathesis reaction was carried out with an excess of 1‐octene in the presence of the catalyst WCl6/(CH3)4Sn. In crosslinking with dicumyl peroxide, the best results were obtained with 10 to 30 wt.‐% of EPR and medium crosslinking degrees. Analysis of sulphur vulcanizates (received with the accelerator N‐cyclohexyl‐2‐benzothiazyl sulphenamide) gave tolerable results only for low sulphur contents (1.5 wt.‐%). Determination of EPR was also possible in non‐crosslinked blends with BR.