Morphology, mechanical behavior, and prediction of A-glass/SiO2/epoxy nanocomposite using response surface methodology

Response surface methodology (RSM) is used to study the mechanical and morphological properties of glass fiber (GF)/epoxy composites. The Box–Behnken method was used to design the experiments and quantify the effects of GF content, glass fiber length (GFL), and silica nanoparticles (SiO₂). Each variable consisted of three levels: GF (5, 10, and 15 wt%), GFL (3, 6, and 9 mm), and SiO₂ (۰, ۰٫۷۵, and 1.5 wt%). Tensile tests were performed to obtain the tensile strength and elongation at break of the samples, and morphology properties were studied by a scanning electron microscope (SEM). The results showed that at high levels of GF, the tensile strength, and elongation at break decreased up to 42% and 30%, respectively. Although increasing the GFL from 6 mm to 9 mm deceased tensile strength by 13%, the elongation at break increased by 7%. The presence of SiO₂ at medium level in the composites decreased the elongation but enhanced the tensile strength by 10%. In addition, RSM was employed to develop the mathematical model between process variables. The developed models were validated by the analysis of variance. The R² obtained from analysis of variance results and normal probability plots showed that the experimental data had a good agreement with those predicted by the models (above 0.95 for all responses).