| Carbon fiber/epoxy resin composites have been widely used in the multi-functionalstructural components such as satellite vehicles,solar panels and antennas,as well as the fields of unmanned aerial vehicles and microelectronic equipment,due to their advantages of high specific strength and modulus,low coefficient of thermal expansion,high designability,good fatigue resistance,corrosion resistance and dimensional stability.As an advanced material,carbon fiber composites have become one of the important indicators to measure the level of technical development for a nation.However,these materials with poor thermal conductivity and heat resistance have become increasingly difficult to meet the development requirements of high frequency and high integration in the electronic information age.Coupled with the shortcomings,such as matrix cracking and delamination under low velocity impact,the application fields of epoxy resin composites are restricted.Therefore,synergistically improving the thermal conductivity and interlaminar toughness of resin matrix composites has become a bottleneck problem to be solved urgently.In this paper,the mechanics,dynamic thermodynamic property,thermal conductivity and interlayer toughness of the composite laminates were studied based on the curing kinetics of the prepregs.As a result,the fiber/epoxy resin matrix composites with high thermal conductivity and interlaminar toughness were obtained,and the concept of“Structural-Functional Integration”was realized.The mechanism of heat conduction and interlayer toughening of laminates was analyzed,which provided a significant theoretical basis for the research and application of high value-added composite products.The optimal curing process of E-glass and carbon fiber/epoxy resin prepregs were obtained by nth-order curing kinetic equation and T-?extrapolation method.The flexural strength,impact strength and thermodynamic properties of[0]10,[+45/-45]5sand[0/90]5slaminates prepared with compression molding method were investigated,respectively.The results show that the curing process of E-glass and carbon fiber/epoxy resin prepregs is120?/60 min+160?/30 min and 130?/60 min+160?/30 min,respectively.The flexural strength of[0]10,[+45/-45]5sand[0/90]5scarbon fiber/epoxy resin laminates is1378,97 and 689 MPa,which is 254%?34.5%and 229%higher than that of E-glass fiber/epoxy resin laminates.Due to the high strength and modulus of carbon fiber and the amounts of 0°fibers,the comprehensive properties of advanced carbon fiber/epoxy composites were more excellent.Therefore,the thermal conductivity and interlaminar toughness of[0]10carbon fiber/epoxy laminates were studied.In order to obtain the epoxy resin matrix composites with high thermal conductivity,[0]10carbon fiber/epoxy resin laminates with different contents of hexagonal boron nitride(h-BN)coating were prepared by compression molding method.The mechanical,thermodynamic,thermal conductive properties and heat conduction mechanism of the laminates were investigated,respectively.The results show that the thermal conductive performance and thermal stability of the composites are improved by adding BN coating.When the BN content is 7 wt%,the thermal conductivity of the laminates reaches the highest values of 0.89 and 0.99 W·m-1·K-1at 25?and 100?,respectively,which are98%and 102%higher than that of pure laminate.When the BN content is 10 wt%,the initial temperature of thermal degradation(Tinitial)of the prepreg is 370?,which is 10?higher than that of unmodified prepreg.BN particles uniformly dispersed in the interlaminar resin form a dense"heat conduction network"to improve the thermal conductivity of the laminates.However,the flexural strength and interlaminar fracture toughness of the laminates are reduced by adding BN,so it is necessary to improve the interlaminar toughness of the laminates as well as the thermal conductivity.In order to synergistically improve the thermal conductivity and interlayer toughness of carbon fiber/epoxy resin composites,carboxylated multi-walled carbon nanotubes(MWCNTs),polyether ether ketone(PEEK)and their synergistic toughening fillers reinforced[0]10carbon fiber/epoxy resin laminates were prepared by interlaminar coating-molding process.Then the mechanical,thermal and dynamic thermodynamic properties were tested,and the mechanism of interlaminar toughening and heat conduction was analyzed.The results show that the mechanical and thermal conductive property of the composites are improved obviously by the synergistic toughening fillers.The mode?interlaminar fracture toughness,flexural strength and impact strength of 0.5 wt%MWCNTs+2wt%PEEK/laminate are 1404 J/m2,1513 MPa and 277 k J/m2,respectively,which are 81%,9.8%and 42%higher than those of pure laminate.At 25 and 100?,the thermal conductivity of 0.5 wt%MWCNTs+2wt%PEEK+3 wt%BN/laminate reaches0.96 and 1.07 W·m-1·K-1,respectively,which is increased by 113%and 118%compared with the unmodified laminate.MWCNTs and PEEK uniformly dispersed in the resin can toughen the resin,improve the bonding strength of fibers and resin,and hinder and deflect cracks,resulting in the improvement of the mechanical properties of the laminate.In addition,a dense“thermal conduction path network”can be constructed between the fillers to improve the thermal conductivity of the composites. |
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