The Study Of Preparation And Mechanical Properties For Basalt Fiber/epoxy Composites Modified With Rare-earth

Considering surface characteristic of basalt fiber and the unique physicochemical properties of rare-earth elements, this paper developed a kind of basalt fibre/ epoxy resin composite with epoxy resin as its substrate and the basalt fiber,which has been surface modified by rare earth solution, as reinforcement. Fourier transform infrared spectroscopy(FT-IR), X-ray photoelectron spectroscopy(XPS), scanning electronic microscopy(SEM) and Electronic universal mechanical testing machine were employed to characterize the chemical construction, microstructure of the basalt fiber before modification as well as the mechanical properties and stretching section appearance. And the function mechanism of RE elements on the basalt fiber and the interface of the composites was discussed according to the results, providing a theoretical support for the mechanical property development of basalt fibre/ epoxy resin composites.Firstly, the investigation into the surface modification of basalt fiber indicated that acidizing made no difference in the micro morphology, that high carboxyl content on the surface provided an active region for the RE to modify the fiber surface and that the higher concentration of RE solution generated new active groups, the largest number of which was obtained when the RE solution concentration was 0.5wt%. According to the SEM microstructure, with the increased RE concentration, the initial spotted structure gradually agglomerated into a dense particle cover on the surface of fiber while in the later stage, large particle of crystals showed up and the cover cracked.Secondly, the mechanical properties of composites had something to do with the RE solution used in pretreatment, namely that the tensile strength, elasticity modulus, bending strength and elasticity modulus all increased at first and then decreased in the wake of the higher RE concentration solution, with the peak value obtained when the RE concentration was 0.5wt%. The SEM tensile fracture morphology indicated that the composites performing well in mechanical properties were the ones that performed very well in interface bonding whose fracture surface contains large amount of residual epoxy resin matrix, because the ideal interface bonding could transmitted external collapsing force effectively.Finally, the function mechanism of RE elements on the chemical structure of surface modified basalt fiber and on the mechanical properties of the composites were analyzed. The RE elements participated into coordination chemistry reaction with the C, H, O of the fiber surface and into the chemical coordination bonding with the active group of the RE modification solution, which improved the activity of the fiber surface, leading to an easily bonded interface layer of higher toughness and accordingly good mechanical properties of the composites. Besides, the modification increased the basalt surface roughness, which enhanced the engaging force in the bonding and provided a stronger destructive friction on the surface,resulting in a better interface bonding.