On the mechanical characterizations of unidirectional basalt fiber/epoxy laminated composites with 3-glycidoxypropyltrimethoxysilane functionalized multi-walled carbon nanotubes-enhanced matrix

This study represents the effects of multi-walled carbon nanotubes at various contents with respect to the matrix (0-0.5wt% at a step of 0.1wt%) on the mechanical responses of unidirectional basalt fiber/epoxy composites. Toward this end, multi-walled carbon nanotubes were firstly functionalized with 3-glycidoxypropyltrimethoxysilane to improve their dispersion state and interfacial compatibility with the epoxy. Subsequently, unidirectional basalt fiber/epoxy and multiscale 3-glycidoxypropyltrimethoxysilane-multi-walled carbon nanotubes/unidirectional basalt fiber/epoxy composites were prepared. The mechanical properties of the composites were determined by tensile, flexural, and quasi-static compression tests. The compressive strength of the composites was obtained through performing the compression test on the off-axis specimens and extracting their longitudinal compressive strength. Results demonstrated that the highest values in tensile strength, flexural strength, and compressive strength were attained at 0.4wt% multi-walled carbon nanotubes with 12%, 38%, 41% increase, respectively, compared to the basalt fiber/epoxy composite. Potential mechanisms behind these were implied. Furthermore, compressive modulus and strength of the specimens were obtained theoretically using an Euler-Bernoulli beam-based approach. Knowing the flexural strength as well as the tensile and flexural moduli from the experimental testing, compressive modulus and strength were obtained and the results were compared to those obtained experimentally. The theoretical and experimental results confirmed that there was a good agreement between them.