Tensile and flexural properties of basalt fibers/nano-alumina powder-reinforced multi-scale composites

Basalt fiber-reinforced epoxy (BFRE) composites without nano-alumina (NA) (Al2O3) and the corresponding multi-scale-nano-composites multi-scale composites containing NA (0.5, 1, 3 and 5 wt.%) were fabricated. Tensile and flexural tests were conducted to study the effect of NA addition on the composites. Surface modification of the NA was carried out using 3-(trimethoxysilyl)propylamine (as a silane coupling agent) to optimize the interaction of NA with epoxy. Subsequently, an infrared spectroscopy test was performed to confirm this surface modification had generated 3- aminoproxyl functional groups on the NA surface. Different weight percentages of surface-modified NA were dispersed in the epoxy resin by mechanical and ultrasonic mixing methods. The resulting mixtures were then used as the matrices for multi-scale BFRE composites. Scanning electron microscopy (SEM) was used to investigate the fracture morphology of the composites after tensile and flexural tests. The greatest tensile and flexural property improvements compared to the control sample (BFRE composites without nano-materials) were obtained by adding 1 wt.% of NA. Upon the incorporation of 1 % NA into the BFRE, there was an improvement in tensile stiffness, increasing from 3.17 to 3.67 GPa. Additionally, the flexural modulus experienced enhancement, rising from 180 to 208 GPa. Improvements were achieved in the tensile and flexural moduli as well as in the tensile and flexural strengths. Microscopic studies also showed the interfacial adhesive enhancements between basalt fibers and the epoxy matrices due to the NA addition.