Enhancement of tensile and flexural strengths of carbon/ramie/epoxy hybrid composites using surface treatment technique: an experimental and artificial neural network study

This study examines the influence of sodium hydroxide treatment on the tensile and flexural properties of carbon/ramie/epoxy hybrid composites, validated through artificial neural network modeling. Among untreated, 1 wt.%, and 5 wt.% sodium hydroxide-treated samples, the 3 wt.% treatment showed the highest improvements, achieving a tensile strength of 524 MPa and a flexural strength of 697 MPa, with respective increases of 27.48% and 43.75%. 1 wt.%, 3 wt.%, and 5 wt.% of sodium hydroxide degraded the ramie fibers, causing weight losses of 4.6%, 8.5%, and 18.5%, respectively. Fourier transform infrared spectroscopy confirmed the removal of surface impurities such as wax, hemicellulose, and lignin, enhancing the bonding between the fibers and the matrix, while field emission scanning electron microscopy revealed improved structural integrity. The superior properties of the 3 wt.% sodium hydroxide-treated composite were attributed to a stronger interface between the fibers and the matrix. Additionally, the artificial neural network model accurately predicted the tensile and flexural strengths using time, load, and extension as inputs, with regression coefficients of 0.99998 and 0.99982 and a minimal error of 3.29%. These results highlight the optimal performance of 3 wt.% sodium hydroxide-treated composites as sustainable materials for structural applications in the automotive, aerospace, and construction sectors.