| Carbon fiber reinforced epoxy resin(CF/EP)has the characteristics of light weight,high specific strength and high stiffness,and is widely used in civil and military fields.However,some properties of CF/EP is still not ideal,it is difficult to meet the application requirements,therefore the CF/EP needs to be modified.Current studies have shown that graphene-based materials(graphene(GR),graphene oxide(GO)and reduced graphene oxide(RGO))have achieved good results in modifying CF/EP due to their unique structure and properties.Research on GR,GO and RGO has a profound significance for the modification of CF/EP.The modified CF/EP composites were prepared by using these three kinds of graphene materials to study:(1)Effect of oxidation degree of graphene-based materials on properties of modified CF/EP;(2)the effect of different sizes of GO on properties of modified CF/EP;(3)preliminary study on three-dimensional reduction of graphene oxide(3D-rGO)modified CF/EP.Includes the following three parts:(1)Using aviation grade high temperature resistant epoxy resin 5284 as matrix,study the effect of graphene materials(GR,rGO,GO)with different oxygen group content on thermal properties,mechanical properties and electrical properties of modified CF/EP.The results show that the addition of GR,rGO and GO reduces the maximum exothermic peak temperature of the modified resin and shortens the time required for the modified resin system to reach a certain degree of crosslinking.The effect of GO is most significant.The addition of 0.2 wt%of rGO and GO has a significant increase in the glass transition temperature of the modified CF/EP.0.2 wt%GO/EP increased the interlaminar shear strength of the modified CF/EP,while the modified CF/EP with 0.2 wt%GR and 0.2 wt%rGO decreased.0.2 wt%rGO showed the best improvement in the conductivity of the modified CF/EP,followed by 0.2 wt%GR and 0.2 wt%GO.(2)The CF/EP composites were modified by GO-1(GO-1 is a large size GO)and GO-2(GO-2 is a small size GO).The effects of GO-1 and GO-2 size on the properties of the composites before and after heat-moisture treatment and the thermal curing properties of the modified composites were investigated.The results show that GO-1 and GO-2 contribute to the glass transition temperature(Tg)of the modified CF/EP and maintain the Tg after the heat-moisture treatment.Under normal conditions,the Tg increase of 0.2wt%GO-2/CF/EP is more obvious;after the heat-moisture treatment,although the Tg self-retention rate of GO-1 and GO-2 modified CF/EP is low,however,when the content of GO is 0.1 wt%and 0.2 wt%,the Tg of the modified composite is still comparable to that of CF/EP.The content of 0.1 wt%and 0.2 wt%of GO-1 and GO-2 contributes to the enhancement of modified CF/EP's interlaminar shear properties before and after the heat-moisture treatment.Under normal conditions,the interlaminar shear strength of 0.1 wt%GO-2/CF/EP is higher;after heat-moisture treatment,the interlaminar shear strength of 0.2wt%GO-1/CF/EP is higher,the retention rate is also the highest among the modified composites.(3)Preparating 3D-rGO/CF and 3D-rGO/CF/EP,and observating microscopic morphology.The results show that before the external force pressing 3D-rGO/CF,rGO is attached to CF,and the upper layer of 3D-rGO is in three-dimensional network state;after external force pressing 3D-rGO/CF,the three-dimensional structure is maintained,which gave the EP the possibility to complete the dipping.Observing the microscopic morphology of 3D-rGO/CF/EP,it was found that the dipping of EP in the 3D-rGO,CF and 3D-rGO/CF interfaces was good,and the surface of CF changes from a smooth surface to a rough surface to which the rGO/EP layer is attached. |
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