Abstract
The effect of accelerator type on processability and mechanical properties of 60/40 natural rubber/ethylene propylene
diene monomer (NR/EPDM) blend was investigated. Three groups of commercial accelerators were selected, i.e.,
sulfenamide group (Santocure-TBBS), thiuram group (Perkacit-TMTD) and mercapto group (Perkacit-MBT and
Perkacit-MBTS). The results reveal that the accelerator type not only affects the cure characteristics, but also has great
influence on compound viscosity. Among the accelerators studied, TBBS gives the best processing safety together with a
relatively high state of cure. In addition, TBBS also provides good cure compatibility between the NR and EPDM phases,
giving rise to superior mechanical properties. Although TMTD could give a high state of cure, it causes severe cure
incompatibility, leading to poor tensile strength. Due to their lower reactivity, the two mercapto accelerators give a
relatively low state of cure. Therefore, the vulcanizates obtained possess low modulus and hardness as well as degree of
elasticity. Surprisingly, it is found that the tensile strength of the MBTS-cured blend is relatively high. Good cure
compatibility given by MBTS could be used to explain the results.
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