Effect of Metal Oxide Fillers on the Thermo‐Mechanical and Physical Properties of Kenaf–Carbon Fiber Epoxy Hybrid Composites

ABSTRACT This study analyzes the effect of MgO, Al 2 O 3 , and TiO 2 metal oxide fillers on the physico‐mechanical and thermal behavior of kenaf/carbon fiber‐reinforced epoxy hybrid composites. Pb 3 O 4 ‐treated kenaf fibers were combined with carbon fiber mats to create a kenaf–carbon–kenaf (KCK) layered system, fabricated using the hand lay‐up method. Metal oxide fillers were added at concentrations of 1% and 2% to examine their effects on mechanical and physical properties. The tensile test results revealed that the 2% MgO delivered the highest strength of 93.74 MPa, surpassing the control sample (91.3 MPa) and also outperforming the Al 2 O 3 and TiO 2 incorporated sample. Flexural strength reached the maximum of 128.28 MPa with 2% of MgO, which is 41.98% higher than that of the control sample (90.35 MPa). The maximum impact strength was obtained at 2% Al 2 O 3 at 56.4 KJ/m 2 , a 37.46% increase from the control sample (41.03 KJ/m 2 ). In terms of moisture resistance, 2% TiO 2 demonstrated the best performance, showing the lowest water absorption. Additionally, the inclusion of metal oxide fillers improved the thermal properties. The higher diffusivity of 2% TiO 2 (0.198 mm 2 /s) and MgO (0.191 mm 2 /s) with lower volumetric specific heat (1.24 MJ/m 3 ·K) indicates rapid heat transfer, whereas the lower diffusivity of Al 2 O 3 (0.147 mm 2 /s) and the control (0.116 mm 2 /s) with higher volume specific heat favors insulation performance. Al 2 O 3 at 2% provides high thermal conductivity while maintaining moderate heat retention. Morphological analysis revealed that 2 wt.% MgO incorporated samples had good fiber‐matrix adhesion, but increased Al 2 O 3 and TiO 2 loadings had voids and agglomeration.