Elastomeric composites of nitrile butadiene rubber reinforced with melanin.

Elastomeric composites comprised of nitrile butadiene rubber (NBR) with the biopolymer melanin were prepared with varying concentration of melanin. We find that the addition of melanin to NBR has no negative effects on the mechanical properties of NBR while improving its resistance to UV and chemicals. The oblong melanin particles act as a filler, increasing the mechanical modulus, but unlike most conventional fillers they do not reduce the toughness of the material. This is partly due to the observed lower crosslinking density in the samples with melanin. Although some chemical linking of the particles to NBR is likely, no appreciable changes were observed in the dynamics of both the segmental and secondary motions of NBR.