Effect of single-walled carbon nanotubes on the cure and mechanical properties of reclaimed rubber/natural rubber blends

Reclaimed rubber (RR) is a recovered rubber material and has lower quality and properties compared to virgin rubber. To enhance its properties and subsequently widen the scope of applications, it is often blended with virgin natural rubber (NR). However, properties of the resultant RR/NR blends are negatively affected as the proportion of RR in the RR/NR blends is increased. This study seeks to explore the use of single-walled carbon nanotubes (SWCNTs) in RR/NR blends, where the dominant component is RR. Based on the tensile properties of specific formulations, the amounts of SWCNTs were first optimised by mixing varying amounts of SWCNTs and NR using conventional laboratory equipment. The effect of optimised SWCNTs on the cure and mechanical properties of RR/NR blends was thereafter investigated. The obtained results showed that upon the incorporation of SWCNTs, the minimum torque of RR/NR blends decreased while the scorch time and cure rate increased. Both the ultimate tensile strength and modulus at 100 %, 300 % and 500 % elongation increased, while the elongation at break slightly decreased. Furthermore, it was found that SWCNTs considerably increased hardness of RR/NR blends but insignificantly decreased the rebound resilience.