Cure kinetic and network structure of NR/SBR composites reinforced by multiwalled carbon nanotube and carbon blacks

• We compared influence of high structure carbon black and nanotubes on cure characteristics of NR/SBR composites.
• We investigated the interfacial interaction by Kraus interaction parameter.
• We modeled the cure kinetics of NR/SBR composites using semi-empirical kinetic model.
• We concluded that the network structure and cure kinetics of CB filled rubber was greatly governed by the bound rubber and its content.

Low structure carbon black (CBN330), conductive high structure carbon black (CBXE2B) and carboxylated multiwalled carbon nanotube (MWCNT) were loaded into the blend of natural rubber (NR) and styrene butadiene rubber (SBR) at different contents up to 10 phr. Kraus plots showed that all the reinforcements interact with NR/SBR blend appropriately. However, the CBXE2B whose interfacial area is the highest showed greatest value of Kraus interaction parameter. Flory–Rhener model and effective torque value revealed that all of the reinforcements enhanced the crosslink density, among them CBXE2B showed the highest impact and MWCNT placed in the second rank. It was also shown that the cure kinetic is affected considerably by incorporating all three reinforcements, resulting in lower scorch time and higher cure rate. It was concluded that the network structure and cure kinetic of CB filled rubber was greatly governed by the bound rubber and its content.