Abstract The flexural strength and impact energy absorption capacity of a material are critical factors for ensuring the durability and safety of components. Epoxy nanocomposites containing α-MnO 2 show promise for structural applications. This study investigates the flexural and impact energy absorption properties of α-MnO 2 -epoxy nanocomposites, which have not been extensively explored in previous research. Nanocomposites with varying weight percentages of α-MnO 2 in epoxy were prepared using ultrasonication dispersion, combined with mechanical mixing technique. X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry were employed to analyze the phase composition, surface morphology, and glass transition temperature of the materials. The successful synthesis of α-MnO 2 epoxy nanocomposites was confirmed by X-ray diffraction analysis and microscopic imaging. The three-point bend tests demonstrated that incorporating α-MnO 2 into the epoxy matrix reduces its flexural stress and strain. Specifically, the flexural stress of specimens with 0.1 wt%, 0.3 wt%, and 0.5 wt% loading decreased by 2.85%, 9.49%, and 26.7%, respectively, while the corresponding flexural strain values decreased by 6.35%, 19.36%, and 28.57%, respectively, compared to pure epoxy. Conversely, the flexural modulus increased by 1.2% and 27.99% for 0.1 wt% and 0.3 wt% loadings, respectively, but decreased by 6.17% at 0.5 wt% loading. Thus, the flexural modulus improved with α-MnO 2 addition up to 0.3 wt%. Drop weight impact tests revealed that the energy absorption capacity of nanocomposites containing 0.1 wt%, 0.3 wt%, and 0.5 wt% α-MnO 2 decreased by 11.26%, 15.73%, and 21.57%, respectively, relative to pure epoxy. Therefore, the impact test results also indicate a reduction in energy absorption capacity with increasing α-MnO 2 content. This decline in flexural stress, flexural strain, and energy absorption capacity is attributed to the filler material’s shape, pore formation during the sample fabrication, and the presence of agglomerated α-MnO 2 within the epoxy matrix, which elevates stress concentrations. Fractography analysis further revealed that the material exhibited brittle fracture rather than ductile deformation during testing.
Hussain et al. (Sat,) studied this question.