Vulcanization kinetics of acrylonitrile-butadiene rubber reinforced with graphene oxide and reduced graphene oxide in the absence of co-cure accelerator

The market demand for elastomeric-graphene/derivatives nanosheets (GDS) materials is high nowadays, due to their excellent physico-mechanical properties over traditional composites. However, the curing behavior of elastomeric-GDS which influences the overall properties and also determines the cost of related products has not been well investigated. Previously, the curing properties of NBR-graphene oxide (GO) and NBR-reduced graphene oxide (rGO) was studied and the curatives (accelerator and activators) were suspected to have influence on their curing behavior. This study explores the curing behavior of NBR-GO and NBR-rGO in the absence of tetramethylthiuram disulfide (TMTD) accelerator. The virgin NBR exhibited shorter curing periods with higher curing rates (CRI) than the composites. The measured CRI showed close correlation with the activation energy E_a, deduced from Ozawa and Kissinger kinetics models. The NBR-rGO composites showed shorter scorch time and lowered E_a at higher temperatures, with increased tensile properties than NB-GO composites. Despite the delay, the composites exhibited high strength over the virgin NBR, due to tighter networks introduced by rGO and GO sheets within NBR. Therefore, future design of elastomer-GDS-based composites must involve a careful control of the amounts of the accelerator-/co-accelerator-like TMTD in the mixtures for improved physico-mechanical properties of the final product.