Polyurethane-nitrile rubber blends

Polyurethane (PU)/nitrile rubber (NBR) blends of different compositions were prepared by a combination of solution blending and mastication process. The thermal, mechanical, dynamic mechanical, and morphological properties indicated synergistic behavior of the two components. Incorporation of NBR in PU showed an increase in the % elongation, thermal stability and solvent resistance of the PU network, while the PU network could attribute improved tensile strength to NBR. The blend rich in PU exhibited optimum tensile strength, whereas the blends rich in NBR exhibited optimum % elongation at break. Morphology revealed that the minor component was dispersed in the major continuous phase. DMA showed the existence of two separate glass transitions. The loss tangent plots showed inward shift of the two peaks with increasing the NBR content indicating increasing miscibility. The increase in carbon black content in blends increased the stress-strain properties up to some extent.