THE ROLE OF HYDROGEN-BONDED INTERPHASE IN ACHIEVING OPTIMAL PERFORMANCE OF NITRILE BUTADIENE RUBBER/GRAPHENE OXIDE NANOCOMPOSITES

Talia Tene¹Lala Gahramanli²Mustafa Muradov²Aynur Mammadova³Vugar Khudaverdiev⁴Aida Azizova⁴Shafiga Alakbarova²Lala Isayeva²Rashida Huseynzade²Goncha Eyvazova²Flora Hajiyeva²Stefano Bellucci⁵Cristian Vacacela Gomez^6*Haji Vahid Akhundzada⁷Rana Khankishiyeva^8*

• ¹Universidad Tecnica Particular de Loja, Loja, Ecuador
• ²Baku State University, Baku, Azerbaijan
• ³Technology of Organic Substances and High Molecular Compounds, Chemical Engineering, Azerbaijan, Baku, Azerbaijan
• ⁴Institute of Radiation Problems, Ministry of Science and Education of the Republic of Azerbaijan, Baku AZ1143, Azerbaijan, Baku, Azerbaijan
• ⁵National Institute of Materials Physics, Atomistilor str. 405 A, Magurele 077125, Romania, Magurele, Azerbaijan
• ⁶Universita della Calabria, Arcavacata di Rende, Italy
• ⁷ICRL Industrial Chemistry Research Laboratory, Baku State University, Z. Khalilov Str. 23, Baku AZ1148, Azerbaijan, Baku, Azerbaijan
• ⁸Azerbaijan University of Architecture and Construction, Baku AZ1073, Azerbaijan, Baku, Azerbaijan

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 concentrated 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 ~2237 cm⁻¹ preserved its position but showed a slight increase in bandwith, consistent with the formation of a hydrogen-bonded interphase. 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 (10²–10⁶ Hz, 20– 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 with incipient aggregation and reduced dielectric stability. Keywords: NBR, GO, rubber nanocomposites, filler dispersion, mechanical properties, thermal stability, interfacial interaction, agglomeration