Influence of strain amplification near crack tip on the fracture resistance of carbon black-filled SBR

Singularity of strain field at the crack tip of elastomeric material has recently attracted considerable attention. For SBR filled with four different types of carbon black, the strain distribution at the crack tip of the single-edge notched tension specimens are investigated using digital image correlation (DIC) and finite element analysis (FEA). Both DIC and FEA results demonstrate that the larger the carbon black particle size, the less strain amplification at the crack tip of SBR. However, the strain amplification region obtained from FEA simulation is much smaller than the strain amplification observed from DIC, and the reasons are discussed. Critical J-integral (J_IC) and tearing modulus (T_R) are calculated via J-integralmethod and are connected to crack initiation and propagation resistance of the SBR, respectively. With increasing carbon black particle size, both J_IC and T_R decrease. Similar trends also occur for tearing energy deduced from the dynamic mechanical thermal analysis. These results are in agreement with the prediction based on strain amplification at the crack tip.