Abstract
This work investigates the mechanical and thermal behavior of epoxy composites reinforced with rice husk powder and silane-treated beetroot stem fibers, with a focus on flammability, fatigue, creep, and dynamic mechanical analysis (DMA). The treatment increased fiber-matrix bonding and interfacial adhesion by using Araldite LY556 resin with Triethylene tetramine HY951 catalyst and 3-APTMS as a silane coupling agent. The treated reinforcements were mixed with the resin to create the composites, which were then cast and cured to increase their strength and longevity. Composite D, which contained 40 vol.% silane-treated beetroot fiber and 3 vol.% silane-treated rice husk powder, demonstrated exceptional fatigue resistance among the samples. It was able to withstand 24,711 cycles at 25% UTS, 21,711 at 50% UTS, and 18,741 at 75% UTS because of the ideal filler-fiber synergy that facilitates load transfer and inhibits the growing of cracks. With a storage modulus of 4.8 GPa at 82°C and a decreased loss factor of 0.58 at 78°C, which indicate enhanced mechanical stability and decreased energy loss, the DMA results validated its higher stiffness. Due to a strong char barrier that prevents heat transfer, Composite E, which had a greater 5 vol.% rice husk filler, had superior flame retardancy and creep resistance. It had the shortest flame spread at 5.84 mm/min and a UL-94 V-0 rating without drops or ignite. While filler aggregation at higher loadings generated stress concentrations, highlighting the requirement for balanced dispersion, SEM images showed homogeneous filler distribution at lower concentrations, improving load bearing. By significantly improving composite performance overall, silane treatment positions these materials as viable options for demanding high-strength, thermally stable applications in the automotive, marine, and aerospace industries.
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