Green-synthesized ZnO-functionalized Passiflora foetida Fiber/Epoxy Biocomposites: Mechanical, Thermostructural and Antibacterial Performance
J. Environ. Nanotechnol., Volume 15, No 3 (September 2026) pp. 215-228
Abstract
This study investigates the preparation and characterization of environmentally sustainable epoxy composites reinforced with Passiflora foetida fibers and ZnO nanoparticles green-synthesized using guava (Psidium guajava) leaf extract. The combined incorporation of Passiflora foetida fiber and guava-leaf-mediated ZnO nanoparticles into an epoxy matrix has been scarcely investigated, particularly for simultaneously improving its mechanical, thermal, dimensional, and antibacterial properties. Composite laminates were fabricated with fiber volume fractions of 10, 20, 30, and 40 vol.% and ZnO nanoparticle contents of 0, 1, 2, and 3 vol.% using the hand lay-up process. The fabricated composites were evaluated for their tensile, flexural, absorbed impact energy, hardness, physical, structural, thermal, and antibacterial properties. The composite containing 30 vol.% Passiflora foetida fiber and 2 vol.% ZnO nanoparticles exhibited the optimum mechanical performance, achieving a tensile strength, flexural strength, absorbed Izod impact energy, and hardness of 41.25 MPa, 75.4 MPa, 2.78 J, and 94.3 Shore D, respectively. FTIR, XRD, SEM, and TGA results provided supporting evidence of favorable fiber–matrix interactions, increased crystalline ordering, comparatively uniform nanoparticle distribution, and improved thermal stability in the optimized composite. The onset of major thermal degradation occurred at approximately 300 °C. The antibacterial activity of the optimized composite was evaluated against Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) using the agar disc-diffusion method. The composite exhibited inhibition zones of 22.8 ± 0.7, 20.9 ± 0.6, 18.6 ± 0.5, and 16.9 ± 0.5 mm, respectively, indicating antibacterial activity primarily associated with the contribution of the green-synthesized ZnO nanoparticles. Overall, the optimized composite demonstrated a favorable balance of mechanical performance, thermal resistance, dimensional stability, and antibacterial activity. These findings indicate its potential for interior components, furniture, packaging, and hygienic material applications, subject to further application-specific validation.
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Reference
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