As an efficient reinforcing material in resin matric composites, the application of basalt fibers (BFs) in composites is limited by the poor interfacial adhesion between BFs and the resin matrix. In this study, to obtain the basalt fibers/epoxy resin composites with enhanced mechanical properties, the modification solution containing different concentrations of Lanthanum ions (La³⁺) was synthesized to modify the BFs surfaces to enhance the poor interfacial adhesion between BFs and the matrix. The morphology, the chemical structure and the chemical composition of the modified BFs surface were observed and detected by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The results show that, after BFs were soaked in the modification solution, the more active groups (C=O, –OH, C–O, etc.) were introduced to the BFs surfaces and effectively enhanced the bond strength between BFs and the resin matrix. The obtained mechanical performances of prepared basalt fibers/epoxy resin composites showed that the tensile strength, bending strength and interlaminar shear strength (ILSS) were improved with the modified BFs, and reached to 458.7, 556.7 and 16.77 Mpa with the 0.5 wt.% La. Finally, the enhancement mechanism of the modification solution containing La element is analyzed.

With increasing attention being paid to environmental issues, the application of natural fibers in fiber-reinforced composites has attracted more and more attention. Composite materials with basalt fibers (BFs) as reinforcement have excellent properties and are widely used in many fields. Hydrothermal aging crucially influences the durability of basalt fiber/epoxy resin composites (BF/ERCs). In this study, BFs were used as reinforcing materials, whose surfaces were modified with a rare earth modification solution (CeCl₃). The density, mechanical performance, and chemical properties of BF/ERCs subjected to hygrothermal aging were analyzed by the weight method, static mechanical performance testing, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The effects of the modification solution with different Ce concentrations on the water absorption, tensile, bending and interlaminar shear strength (ILSS) of BF/ERCs were investigated. The test results showed that the water absorption of BF/ERCs treated with a modification solution that contained Ce 0.5 wt % as the minimum value and the retention rate of the mechanical properties of BF/ERCs reached maximum values after hygrothermal aging.