Effects of Fiber Treatment and Humidity on the Mechanical, Fracture Toughness, Dynamic and Thermal Properties of Grewia Optiva Natural Fiber-Reinforced Epoxy Composites

Abstract

Abstract The effects of relative humidity and fiber treatment on the mechanical properties of Grewia optiva natural fibers reinforced composites were studied. The results revealed that the fiber reinforcement composition with benzoyl peroxide (BP) treatment on NaOH-pretreated fiber shows optimum results at 90% relative humidity. The corresponding experimental results of the tensile strength (MPa), percentage elongation, flexural strength (MPa), impact strength (kJ/m2), and fracture toughness (MPa √m) were 260.895, 5.230, 52.572, 33.226, and 2.565, respectively. The surface response method yielded the optimum properties with a D value of 0.768 and properties variation between 1% and 6%. Thermogravimetry analysis shows a considerable amount of variation in the rate of degradation after the chemical treatment of fibers. A decrease in the damping factor and an increase in glass transition temperature due to chemical treatment show increased fiber-matrix interfacial bonding and cross-linking. Scanning electron microscopy images show that BP treatment is more suitable than NaOH treatment to remove the undesirable elements from the fiber surface and higher surface roughness to obtain better bonding between fiber and matrix. The fiber diameter reduction due to BP and NaOH treatment is about 57% and 52.62% as compared to untreated fiber.