Study On Modified Epoxy Resin Composites Toughened By Iron Oxide Hybrid Nanoparticles

Carbon fiber?CF?composite are widely used in many fields due to their good specific strength,specific rigidity and designability.However,there is a problem of interlaminar failure in the practical application of CF composites.its use in high-tech products.was greatly limits Therefore,Therefore,a simple and efficient method to solve the problem of interlaminar failure of CF composites is of far-reaching significance to the popularization and application of CF composites.Among them,improving the fracture toughness of epoxy resin?EP?matrix is considered to be a simple,effective,economical and practical method.In order to improve the fracture toughness of EP(K_IC)and the mode I fracture toughness(G_IC),of CF composites,acicular hydroxyl iron oxide??-FeOOH?prepared by liquid phase deposition-air oxidation was used as precursor.The?-FeOOH was treated by calcination method and electrostatic self-assembly method to obtain composite nanoparticles of iron oxyhydroxide and ferric oxide??-FeOOH@Fe₂O₃?and graphene oxide coated iron oxyhydroxide?GO@?-FeOOH?,respectively,which were used as toughening fillers to improve the fracture toughness of EP and the The mode I fracture toughness of CF composites.And the toughening mechanism of two kinds of composite nanoparticles was described systematically.The research content of this paper is divided into the following four parts:?1?Preparation and characterization of?-FeOOH@Fe₂O₃:?-FeOOH,composite nanoparticles with different saturation magnetization were obtained by calcining?-FeOOH@Fe₂O₃ at different temperature and calcination time.The crystal composition,morphology,magnetic properties and thermogravimetric analysis of the nanoparticles were carried out.The results show that the aspect ratio of the calcined nanoparticles remains unchanged,but the granular matter on the surface of the calcined nanoparticles increases.The saturation magnetization of the nanoparticles calcined at 200,250,300,350?increases with the increase of?-Fe₂O₃ content.?-FeOOH begins to transform into?-Fe₂O₃,at about250C,and with the extension of calcination time and the increase of calcination temperature,the composition of?-FeOOH is gradually transformed into?-Fe₂O₃.?2?Study on?-FeOOH@Fe₂O₃ reinforced EP composites:nano-particles calcined under various conditions were dispersed into EP,and the nanoparticles with suitable toughening effect were selected as fillers to study the orientation effect of magnetic field.Binary composites??-FeOOH@Fe₂O₃/EP?and ternary composites??-FeOOH@Fe₂O₃/CF/EP?were prepared with or without magnetic field.The critical strength factor(K_IC),of?-FeOOH@Fe₂O₃/EP was measured by three-point bending test?SENB?and the mode I fracture toughness(G_IC)of?-FeOOH@Fe₂O₃/CF/EP was measured by double-arm cantilever test?DCB?.The results show that the toughening effect of?-FeOOH@Fe₂O₃was the best under the condition of calcination at 250?for 1 h.The 1 wt%?-FeOOH@Fe₂O₃/EP,K_IC prepared by the particle induced by magnetic field is 2.45MPa.m1/2,which is 84%higher than that of EP and 66%higher than that of?-FeOOH@Fe₂O₃/EP without magnetic field induction.The G_IC of 1 wt%?-FeOOH@Fe₂O₃/CF/EP induced by magnetic field is 0.9 k J/m²,which is 90%higher than that of CF/EP and 50%higher than?-FeOOH@Fe₂O₃/CF/EP without magnetic field induction.?3?Preparation and characterization of GO@?-FeOOH:Usedelectrostatic self-assembly technology,GO and?-FeOOH were used to prepare composite particles GO@?-FeOOH with one-dimensional structure through electrostatic attraction and the reduced nanoparticles?RGO@?-FeOOH?were obtained by reducing the nanoparticles with sodium borohydride.A series of methods were used to characterize and analyze the crystal composition,magnetic properties,chemical structure and morphology of the composite nanoparticles.The experimental results show that the crystal form of GO@?-FeOOH is the same as that of?-FeOOH.The saturation magnetization of GO@?-FeOOH is 1.95 emu/g lower than FeOOH.The content of Czochro double bond on the surface of GO@?-FeOOH is higher than that of?-FeOOH,and the content of reduced RGO@FeOOH Czochro bond is decreased.There are a large number of GO folds in GO@?-FeOOH.and it can be seen from TEM that GO is successfully coated on the surface of FeOOH.?4?Study on GO@?-FeOOH reinforced EP composites:GO,FeOOH,GO@?-FeOOH,RGO@FeOOH were added to EP respectively to prepare corresponding binary composites GO/EP,?-FeOOH/EP,GO@?-FeOOH/EP,RGO@?-FeOOH/EP and ternary composite material GO@?-FeOOH/CF/EP.Using SENB to test the K_IC of binary composites,DCB to test the G_IC of GO@?-FeOOH/CF/EP.The results showed that when the content of GO@?-FeOOH is 0.5 wt%,the K_IC of GO@?-FeOOH/EP is increased by 40%compared with EP.Under the induction of magnetic field,K_IC is increased by 139%compared with the blank sample.The K_IC of?-FeOOH/EP,GO/EP,and RGO@?-FeOOH/EP is 37%,17%and 25%higher than that of the blank sample,respectively.At this content,the G_IC of GO@?-FeOOH/CF/EP increased by 42%compared with CF/EP,and the G_IC of GO@?-FeOOH/CF/EP induced by magnetic field increased by 89%.