Synergistic Reinforcement of <scp>NBR</scp> Composites Using <scp>CNC</scp> – <scp> ZrO ₂ </scp> Dual Phase Filler

ABSTRACT This work presents synergistic reinforcement of zirconia (ZrO 2 ) particles impregnated cellulose nanocrystals (CNC) in acrylonitrile butadiene rubber (NBR). The CNC–ZrO 2 dual phase filler is prepared by in situ grafting of ZrO 2 particles from its precursor (zirconium (IV) propoxide) on CNC via sol–gel route in the NBR solution. Such functionalization of filler enables its better dispersion in rubber matrix. The interaction between ZrO 2 and CNC is established by FTIR and XPS studies, while SEM images reveal homogeneous morphology. The modification of CNC surface by ZrO 2 particles and the anisotropic character of CNC trigger high reinforcing effect of the dual phase filler. This is reflected in the excellent mechanical performance of the NBR composites due to efficient interactions between the filler and rubber chains. For example, tensile strength becomes nine times higher for a particular formulation (In‐CNC 10 ‐Zr 15 ) compared to that of pure NBR. In addition, the tested composites show very good resistance to aging and attack of oil and ozone. This study demonstrates the potential of integrating bio‐derived flexible CNC with inorganic rigid ZrO 2 to offer a multifunctional filler platform for the advancement of elastomer applications.