The Study Of Mechanical Properties For Basalt Fiber/epoxy Composites Modified With LaCl₃

In this study,basalt fiber reinforcements and epoxy resin matrix were researched.In order to the chemical inertness and bad infiltration of the surface of basalt fibers,basalt fibers were dropped into different concentration solution,which with different contents of La element.After that,the treated fibers and epoxy resin were prepared into composites.FT-IR,XPS,and SEM were applied to described the chemical and physical characteristics of fiber surfaces(before and after treated)and analyzed influences of chemical structures,morphologies and elemental compositions with different contents of La element in diverse concentration solution.Electronic universal mechanical testing machine and SEM were applied to described mechanical properties and morphology of composites,respectively.So,the role of La element in fiber surfaces modification and principles of bonding interface between fiber and resin were presented.(1)Fiber surface activity was largely improved by a large number of-COOH,-OH and other oxygen-containing reactive groups were introduced into basalt fiber surfaces which treated in rare-earth modification solution.Moreover,SEM showed that corrosion occurred on fiber surfaces during socked in rare-earth modification solution.Mottled bump structure emerged and surface roughness increased in smooth fiber surface as well.The mottled bump structure coated on the fiber surface and formed a compact membrane structure when La concentration up to 0.5%.But,when the La concentration exceeded 0.5%,the film-structure on the fiber surfaces started to dropped,and then compact film-structure turned into large-grained structure.(2)Comparison on mechanical properties results of composite(before and after treated)showed that: when La concentration was up to 0.5%,tensile strength,bending strength and inter-laminar shear strength maximized,which increased 56.22%,103.32% and 88%,respectively.The residual resin were mostly located on fiber surfaces of fractures.(3)According to special property of La,we also discussed its mechanism of action.When strong chemical affinity coordination bonds were formed between La and non-metallic element like C,H,O,N on the basalt fiber surfaces,the coordination bonds would attached on the fiber surface and introduced oxygen-containing organic active group to the fiber surfaces,which would significantly improved the fiber surface activity.When modified fiber was added into resin matrix,dehydration condensation reaction would take place and form ether bonds or ester bonds between hydroxyl and carboxyl attached on basalt fibers and hydroxyl in resin.At the same time,coordination bonds produced between La on the fiber surface and resins.That made the bonding force vastly increased between these two-phase,which assumed enhancement of mechanical property macroscopically.