Natural rubber–bromobutyl rubber (NR–BIIR) composites containing 0–9 phr COOH-functionalized graphene nanoplatelets (FGNP) were prepared by melt blending using a two-roll open mill. FGNP dispersion and interfacial interactions within the NR–BIIR matrix were examined by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The composites exhibited significant enhancements in mechanical, thermal, and dynamic mechanical properties compared to NR–BIIR gum. At 5 phr FGNP loading, improvements of 22.9, 19, 32.6, 30.2, and 24% were observed in stress at rupture, elongation at failure, modulus at 100% strain, tear resistance and abrasion loss respectively. These improvements are attributed to uniform FGNP dispersion, as confirmed by FESEM and XRD. Enhanced interfacial adhesion was evidenced by increased storage modulus (E′) and glass transition temperature (T_g). Thermogravimetric analysis showed that the T₁₀, T₅₀ and char residue at 600 °C of 5 phr FGNP-reinforced composites were 2.5, 3.2 °C and 102% higher than NR–BIIR gum.

Keywords: natural rubber-bromobutyl rubber blends, functionalized graphene nanoplatelets, mechanical attributes, thermal stability, viscoelastic behaviour.