The role of hydrogen-bonded interphase in achieving optimal performance of nitrile-butadiene rubber/graphene oxide nanocomposites
Talía Tene, Lаla Gahramanli, Mustafa Muradov, Aynur Mammadova, V. G. Khudaverdiev, Aida Azizova, Shafiga Alakbarova, Lala Isayeva, Rashida Huseynzade, Goncha Eyvazova, F. V. Hajiyeva, Stefano Bellucci, Cristian Vacacela Gómez, Haji Vahid Akhundzada, Rana Khankishiyeva
Abstract
Graphene oxide (GO) nanosheets (0.5–2.0 phr) were incorporated into nitrile-butadiene rubber (NBR) to clarify how interfacial chemistry and dispersion control macroscopic performance. GO was synthesized by a modified Hummers method, and different filler concentrations of NBR/GO were prepared via solution–coagulation followed by sulfur vulcanization. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) confirmed multilayer GO and best sheet dispersion at 1 phr, whereas 2 phr showed initial aggregation. Fourier-transform infrared spectroscopy (FTIR) confirmed that the NBR backbone and nitrile groups remained intact, while weak GO-derived C–O–C/C–O bands appeared at higher loadings. The C≡N band at ∼2,237 cm −1 preserved its position but showed a slight increase in bandwidth, consistent with the formation of a hydrogen-bonded interphase. X-ray diffraction (XRD) showed loss of GO periodicity in the rubber matrix. UV-Vis/Tauc analysis indicated a non-monotonic band gap (direct 3.01→3.13→3.11 eV; indirect 2.84→2.92→2.96 eV), arising from confinement at well-dispersed loadings and π–π stacking at higher loadings. Dielectric measurements (10 2 –10 6 Hz, 20 °C–100 °C) evidenced a more stable ε′ for GO-filled samples, maximized at 1 phr. Mechanical testing showed simultaneous gains in tensile strength, tear resistance, and rebound elasticity at low GO loadings, while swelling and thermo-oxidative retention improved due to barrier effects and chain immobilization. Overall, ∼1 phr GO delivers the best structure–property balance, combining hydrogen-bond-mediated interfacial adhesion and optimal dispersion with stable dielectric behavior and reduced swelling/aging sensitivity; 2 phr yields the highest tensile value but also results in incipient aggregation and reduced dielectric stability.