Influence of average monomer sequence length on molecular mobility of acrylonitrile butadiene rubber

Abstract

The dominant factor of inhomogeneous molecular mobility (T2) of acrylonitrile butadiene rubber (NBR), has been studied by pulsed 1H NMR spectroscopy. We investigated the influence of the number-average molar mass of chain length between crosslinks (Mc) and average monomer sequence length of butadiene (LnBU), which is an inhomogeneity of the first ordered structure. The FID analysis shows that vulcanized samples are composed of 3 components with different molecular mobility, T2S, T2M and T2L. Moreover, we evaluated the Mc dependency of T2S, T2M and the 1H ratio and the change of T2S, T2M and the 1H ratio of before and after vulcanization against LnBU. According to the results, the LnBU showed a more dominant correlation to T2 and the 1H ratio than Mc. That implies that the NBR molecular chain with almost the same average monomer sequence length of acrylonitrile mobility at 30°C originates from the inhomogeneity of the first ordered structure of NBR.