Abstract
Summary: The reactive compatibilization of ethylene‐propylene‐diene (EPDM)/nitrile rubber (NBR) blends was performed using mercapto‐modified copolymers (mercapto‐modified EPDM, EPDMSH, and mercapto‐modified ethylene‐vinyl acetate copolymer, EVASH) in combination with oxazoline‐functionalized NBR (NBR‐ox). The best mechanical performance was achieved with the two EVASH‐based compatibilizing systems, especially the one containing the co‐reactive copolymers because of the reactivity of the oxazoline group. The presence of insoluble material in non‐vulcanized blends suggested the reactive compatibilization. The morphologies of these blends were examined through scanning electron microscopy (SEM). Blends compatibilized with the EVASH‐based systems showed finer morphologies than the non‐compatibilized blend or those compatibilized with the EPDMSH‐based systems. In non‐vulcanized NBR/EPDM (70:30 wt.‐%) blends, the presence of the co‐reactive EVASH/NBR‐ox system changes the morphology from a cocontinuous structure towards a droplet‐matrix morphology, and also results in a significant broadening of the damping curve related to the NBR transition, observed from DMTA analysis. The effect of the compatibilization on aging resistance has also been evaluated.
SEM micrograph of a non‐vulcanized NBR/EPDM blend compatibilized with a NBR‐ox/EVASH co‐reactive copolymer.
magnified imageSEM micrograph of a non‐vulcanized NBR/EPDM blend compatibilized with a NBR‐ox/EVASH co‐reactive copolymer.