Physio-mechanical and thermal behavior of kenaf (Hibiscus cannabinus L.) fiber-reinforced epoxy composites: effect of eco-friendly treatment

The current study aims to investigate the application of environmentally friendly fiber surface treatment as a means of reducing the environmental risks associated with traditional chemical treatments. Kenaf fibers’ surface was modified with a (10% (w: v)) aqueous solution of sodium bicarbonate, before being included into epoxy matrix to develop kenaf fiber-based epoxy composites. The duration of the kenaf fiber treatment was 24, 48, 72, and 120 h. It was explored and optimized how the sodium bicarbonate treatment affected the developed composite’s tensile, flexural, and thermal properties. There was no significant effect of sodium bicarbonate treatment on the thermal behavior of the developed composites. The developed composites’ tensile and flexural behavior improved most when the fiber was treated for a full 72 h. The tensile and flexural strength of the epoxy composites comprising treated (72-h) kenaf fibers was found to be 33.31% and 25.55% greater than that of the untreated kenaf epoxy composites. Longer treatment times beyond 72 h resulted in reduced mechanical properties due to fiber fibrillation. The morphological behavior of the developed composites revealed fiber pullout, matrix cracks, pits, void development, and the interfacial bond between the epoxy and kenaf fibers. The results showed that the treated fibers bonded well with the epoxy matrix at the interface, which was supported by morphological investigations. The developed composites have the potential to be used in the production of automobile panels and other lightweight industrial items.