This investigation addresses the evolution of the microscopic and mesoscopic structures distribution, and micro-defects of carbon black (CB) filled natural rubber (NR) under uniaxial tensile condition during the fatigue process. NR was filled with three different grades of CB in order to understand the impact of the structural degree and specific surface areas of CB and fatigue degree on the Payne effect. It was found that the Payne effect was initially suppressed and then enhanced by increasing the degree of fatigue. The decrease of the storage modulus in the low strain area was attributed to the CB network destruction and the breakdown of the matrix cross-linking network in the early fatigue stage. However, by further increasing the degree of fatigue, the spatial rearrangement of CB aggregates with the orientation of molecular chains between adjacent CB aggregates will results in mechanical reinforcement before the appearance of micro-defects. Moreover, it has been demonstrated that the structural degree of CB has a stronger impact on the mesoscopic structures than the specific surface area of CB during the tensile fatigue process.
Keywords: carbon black; fatigue process; mesoscopic structure; microscopic structure; natural rubber; uniaxial tension.