Study On Curing Kinetics And Structure-function Integration Of Carbon Fiber/epoxy Resin Composites Modified By Micro-nano Particles

With the increasing integration of electronic components,the heat generated by the equipment is increasing.The heat dissipation performance of traditional packaging materials is poor,and the heat is not discharged in time,which can easily lead to the decline of the working life of the equipment and the reduction of work efficiency.Therefore,the development of thermal management materials with high thermal conductivity is an urgency to be handled.Carbon fiber epoxy resin（CF/EP）composites prepared from carbon fiber prepregs are widely used in various fields due to their high specific modulus,corrosion resistance,high specific strength,ablation resistance and fatigue resistance.However,composite laminates have problems such as easy cracking between layers,poor fracture toughness,and low thermal conductivity in the thickness direction.How to improve the thermal conductivity and interlaminar toughness of resin matrix composites is a bottleneck problem to be solved,which needs to be further studied.In this paper,BN@Zn O particles were prepared by sol-gel method.The effect of interlayer micro-nano fillers on the curing kinetics of laminates was studied and the optimum curing process parameters were obtained.The CF/EP laminates with synergistic modification of BN@Zn O particles and interlayer toughening of Si C nano whiskers（Si Cnw）were prepared by molding process,and the“structural functional integration”composites with high thermal conductivity and excellent mechanical properties were obtained.The n-order curing kinetic model and two-parameter autocatalytic kinetic model of BN@Zn O modified CF/EP composite laminates were established by non-isothermal DSC method.The two models were compared with the actual curing reaction process.The results showed that the two-parameter autocatalytic kinetic model calculated by Malek method was basically consistent with the actual curing reaction process,which was more suitable for describing the curing reaction process of the BN@Zn O interlayer modified CF/EP prepreg.The curing process parameters of BN@Zn O interlayer modified CF/EP prepreg were determined by T-βextrapolation method.The effects of different curing temperatures and layup methods on the mechanical properties of 2 wt%BN@Zn O composite laminates were studied.The impact strength and flexural strength of the laminates prepared at 130°C/60 min+160°C/30 min were 75%and 193%higher than those prepared at 100°C/90 min,respectively.Under the curing process of 130°C/60min+160°C/30 min,the[0]₁₀laminates showed higher impact strength and flexural strength than the[0/90]₅laminate,which were 113.9%and 67.4%higher,respectively.Finally,the[0]₁₀laying method and the molding curing process of 130°C/60min+160°C/30 min were determined.The effects of different mixing methods of BN and Zn O and the content of BN@Zn O on the mechanical properties and thermal conductivity of CF/EP composite laminates were studied.The results showed that the composite laminates prepared by adding BN coated Zn O（BN@Zn O）particles have better thermal conductivity and interlaminar fracture toughness than the composite laminates prepared by blending BN and Zn O particles（BN/Zn O）.The thermal diffusivity of 10 wt%BN@Zn O composite laminates was 0.667mm²·s^-1and 0.58 mm²·s^-1at 25°C and 100°C,respectively.The thermal conductivity was0.797 W·m^-1·K^-1and 0.925 W·m^-1·K^-1,respectively,which was 78%and 90%higher than that of pure laminates.The impact strength of 10 wt%BN@Zn O composite laminates reached 248 k J/m²,which was 27.2%higher than that of pure laminate.The mode II interlaminar fracture toughness of 2 wt%BN@Zn O composite laminates was 15.4%higher than that of pure laminate.However,with the increase of filler content,the interlaminar fracture toughness gradually decreased.The effects of different contents of Si Cnw and the synergistic effect of BN@Zn O and Si Cnw on the thermal conductivity and mechanical properties of composite laminates were studied.The addition of 0.5 wt%Si Cnw to interlayer of composite laminates has the significantly effect on the improvement of the model II interlayer fracture toughness,reaching 2242 J/m²,which was 188.9%higher than the pure laminate.The mode II interlaminar fracture toughness of 2 wt%BN@Zn O+0.5 wt%Si Cnw composite laminate was 57.6%higher than that of pure laminate.The impact strength of 10 wt%BN@Zn O+0.5 wt%Si Cnw composite laminate reached the highest value of 250 k J/m²,which was 28.2%higher than that of pure laminate.The thermal conductivity of BN@Zn O composite laminates was further improved by adding Si Cnw between the layers.The thermal conductivity of 10 wt%BN@Zn O+0.5 wt%Si Cnw composite laminates increased to 0.937 W·m^-1·K^-1and 1.00 W·m^-1·K^-1at 25°C and 100°C,which were 109%and 105%higher than pure laminates,respectively.The multi-scale synergy of BN@Zn O and Si Cnw can improve significantly the thermal conductivity and interlaminar fracture toughness of composite laminates at lower filler content.