| Carbon fiber reinforced resin composite has received widespread attention in the cryogenic fields, such as cryogenic superconductor, cryogenic storage nitrogen and helium, because of its low density and high strength. However, composite is sensitive to microcrack in the cryogenic environment, its air permeability will be faced with rigorous challenge. Laminal filter’s ordering can distinctly improve the air permeability of resin composite, but filter has bad interface compatibility with resin. Based on this fact, this paper has studied the interface compatibility and air permeability of magnetic modified graphene oxide (GO) reinforced epoxy resin composite.In this paper, magnetic Fe3O4nano-particles (about20nm) were synthesized by the chemical co-precipitation method, which reacted with TEOS and APTES successively to bring in some amino groups in the surface. The introduction of amino functional groups not only increases loading capacity of Fe3O4nano-particles on the surface of graphene oxide, but also improves the interface compatibility of magnetic modified graphene oxide and epoxy resin.Graphene oxide (GO) was prepared from300mesh natural flake graphite through the modified Hummers method. Its aspect was10micrometers or so. There are some carboxyl and hydroxyl groups, that make graphene oxide homodisperse in water and ethanol. We modified the graphene oxide with Fe3O4nano-particles by in situ synthesis method and chemical grafting method respectively. In situ synthesis method destroyed the lamella structure of graphene oxide, and at the same time, loading capacity of Fe3O4nano-particles was limited. On the contrary, chemical grafting method gave us an ideal result, nano-particles distributed uniformly and controllably. When the mass load ratio achieved2:1, amino modified Fe3O4nano-particles almost covered the surface of graphene oxide, its saturation magnetization was20emu/g, and coercivity was20Oe, implying super-paramagnetic. FTIR analysis results show that there are still some amino groups on the magnetic modified graphene oxide.Add the magnetic modified graphene oxide to epoxy resin, we prepared structural disordering composite, SEM intuitively evaluated their interface compatibility, showing that the interface compatibility of magnetic modified graphene oxide and epoxy resin is better than that of magnetic modified expanded graphite and epoxy resin. FTIR and XPS demonstrate that amino groups of Fe3O4nano-particles have taken place Ring-opening addition with epoxy group of epoxy resin, which is the main reason to improve the compatibility.Making elliptical sheet model analyzed laminal filter’s force situation under magnetic field, according to Boltzman function, we calculated the minimum magnetic field needed, it was82.5mT.At last, we adopted0.4T magnetic field to prepare structure ordering composite, in which the mass ratio of magnetic modified graphene oxide was1%.Morphology of cross section indicated that magnetic modified graphene oxide was arranged in order. The XRD diffraction pattern of structure ordering composite is apparently different from the disordering composite in diffraction angle10°,which attributes to the (002) crystal face of graphene oxide. This point further illustrated the highly ordering of magnetic modified graphene oxide.Eventually, helium mass spectrometer leak detector was applied to check helium leakage of composite to analyze the effect of mass ratio of magnetic modified graphene oxide and structure ordering on the air impermeability. The research finding proved that within limits, helium leakage decreased along with the mass ratio increasement of magnetic modified graphene oxide, that is to say, air impermeability of composite becomes better. Moreover, with regard to the same content of magnetic modified graphene oxide of disordering composite, structure ordering composite has better air impermeability. |
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