Preparation and properties of acrylonitrile–butadiene rubber–graphene nanocomposites

Abstract

The graphene oxide (GO) was prepared by sonication-induced exfoliation from graphite oxide, which was produced by oxidation from graphite flakes with a modified Hummer's method. The GO was then treated by hydrazine to obtain reduced graphene oxide (rGO). On the basis of the characterization results, the GO was successfully reduced to rGO. Acrylonitrile-butadiene rubber (NBR)-GO and NBR-rGO composites were prepared via a solution-mixing method, and their various physical properties were investigated. The NBR-rGO nanocomposite demonstrated a higher curing efficiency and a change in torque compared to the gum and NBR-GO compounds. This agreed well with the crosslinking density measured by swelling. The results manifested in the high hardness (Shore A) and high tensile modulus of the NBR-rGO compounds. For instance, the tensile modulus at a 0.1-phr rGO loading greatly increased above 83, 114, and 116% at strain levels of 50, 100, and 200%, respectively, compared to the 0.1-phr GO loaded sample. The observed enhancement was highly attributed to a homogeneous dispersion of rGO within the NBR matrix; this was confirmed by scanning electron microscopy and transmission electron microscopy analysis. However, in view of the high ultimate tensile strength, the NBR-GO compounds exhibited an advantage; this was presumably due to strong hydrogen bonding or polar-polar interactions between the NBR and GO sheets. This interfacial interaction between GO and NBR was supported by the marginal increase in the glass-transition temperatures of the NBR compounds containing fillers.

Effect of graphene on polar and nonpolar rubber matrices

“…For comparison of properties, NBR-GO and NBR-RGO nanocomposites were also prepared as per our earlier work (Mensah et al 2014;Mensah et al 2015). The nanocomposite formulations and the codes of the NBR and EPDM based compounds are presented in Table 1.…”

“…The coating and observation process lasted for~20 min. This method had previously been adopted to study the morphologies of NBR-GO/rGO composites (Mensah et al 2014;Mensah et al 2015).…”

“…Previously, SEM was used to study the dispersion of GO and rGO in a NBR matrix (Mensah et al 2014;Mensah et al 2015). The deeply-embedded GO and rGO sheets in NBR matrix were not seen on the matrix surface initially by the SEM technique.…”

“…Mixing of the GO and rGO into the rubbers generally delayed t s2 especially for the GO filled compounds. The delay in t s2 was established to be caused by absorption of the cure accelerator by the oxygen moieties on the GO/rGO sheet (Hernández et al 2012;Mensah et al 2014;Mensah et al 2015;Rafiee et al 2010;Stankovich et al 2006). However, other factors such as; the acidic nature of the GO/rGO sheets, dispersion, wrinkling nature of the GS, thermal conductivity properties of GS, viscosity of the polymer, content of the curing ingredient (ZnO) used etc.…”

“…That is, GO/rGO and other derivatives graphenes reinforced with various elastomers with different polarities have shown different curing with varied physicomechanical properties (Allahbakhsh et al 2013;Mensah, et al 2014;Mensah et al 2015;Varghese et al 2013). The influence of the corrugating/wrinkling structural texture of the graphene sheet on rubber matrix has shown different findings on resulting properties of the composites by different researchers.…”