Epoxidized polybutadiene rubber as an effective compatibilizer for acrylonitrile butadiene rubber and polybutadiene rubber blend

In the present study, epoxidized polybutadiene rubber (EBR; 30 mol% epoxidation) was synthesized using commercial-grade cis-polybutadiene rubber (BR). The EBR was successfully utilized as an effective compatibilizer between two incompatible elastomers, namely polar acrylonitrile butadiene rubber (NBR) and non-polar polybutadiene rubber (BR). The NBR and BR were blended in varied formulations and studied for morphological and mechanical properties. The observed properties of the blends containing EBR, as a compatibilizer, were compared with analogous blends without EBR. The optimum loading of EBR in NBR/BR formulations was found to be 5 phr (parts per hundred gram of rubber). The significant improvement in various mechanical properties such as tensile strength, tensile modulus, elongation at break and hardness were observed in presence of optimum loading of EBR in NBR/BR blends. Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analyser (DMA) studies revealed that the compatibility between two incompatible rubbers improved in the presence of EBR. The results observed with EBR-compatibilized blends revealed that EBR can be used as an effective compatibilizer between two incompatible rubbers (NBR and BR).