Temperature-dependent crosslinking behaviour of graphene-reinforced rubber nanocomposites

A composites of acrylonitrile rubber (NBR)-graphene(G) and natural rubber (NR)-G prepared with solution mixing technique and cross-linked at 60°C was compared with those prepared with solution and solid mixing method containing G and graphene oxide (GO) cured at 160°C. The comparative analysis was made based on: crosslinking density, N_c(mol/cm³), tensile strength, TS (MPa) and thermal degradation resistance etc. The composites cured at 60°C, generally showed improved properties than those cured at 160°C. For example, NBG_L(G = 0.1phr) and NBG_H(G = 1phr) recorded 73.4 and 35.7% increment in TS respectively than the neat, NB0(G = 0phr). Interestingly, the NRG_H(G = 1phr) recorded 32.4% increase than NR0(G = 0phr). These, exceed TS of NBR filled with G = 0.1phr (G_0.1), G = 1phr (G₁) and 1phr GO (GO₁) cured at 160°C, which recorded 50, 13, and 52.5% respectively higher than NBR. The improvement in properties of samples cured at 60°C than those cured at 160°C was linked to effective dispersions of the G-sheets within the matrices (NBR and NR) and the formation of desired crosslinked structures (NBR—HN—R¹—HN—G—NBR, NBR—G—HN—R¹—HN—G—NBR, NR—HN—R¹—HN—G—NR, and NR—G—HN—R¹—HN—G—NR including polar interactions).