Research On The Properties Of Nano-silver-load Boron Nitride/Epoxy Resin-based Thermal Conductive Composites

As the performance of electronic devices increases and their size shrinks,the power consumption of their internal circuits increases,and excessive heat generation occurs.The accumulation of heat affects the stability,durability and service life of electronic devices.Filled thermally conductive polymers are the mainstream thinking direction to solve this problem.However,inorganic nanoparticles have poor compatibility with polymer matrix,and single particles cannot achieve the ideal thermal conductivity effect,and the blocking of thermal conductivity pathways in the interface will reduce the thermal conductivity of the material.Therefore,this paper solves the above problems by surface coating,two-particle bonding,and the construction of effective thermal conduction pathways.In this experiment,boron nitride（BN）was first coated with polydopamine（PDA）,and single packing particle BN-PDA nanoparticles（BP）with good compatibility with epoxy resin（EP）were prepared.（3-mercaptopropyl）trimethoxysilane was used to modify hydroxyl groups on PDAs to sulfhydryl-containing nanoparticles.Silver（Ag）nanoparticles loaded on the surface of BP were prepared by citric acid,ascorbic acid,potassium iodide and silver nitrate in a pot,and the stability of S-Ag bonds was used to form BN-Ag nanoparticles（BPA）with two-particle fillers.On this basis,cellulose and sodium alginate were blended to form a natural internal network structure,and a skeleton with network structure was prepared by freeze-drying.Finally,AG80 EP was blended with BPA particles,poured on a lyophilized skeleton,and a composite material containing a thermal conduction network（BPA/EP-C）was prepared.In this paper,the micromorphological structure analysis and thermal conductivity,mechanical and electrical properties of the prepared materials were analyzed,and the influence of filler amount and microstructure on heat transfer and its laws were systematically analyzed.The experimental results show that the compatibility of BP/EP becomes better after BP synthesis.When the Ag particles were added,the BN-Ag duoparticles exerted a synergistic effect,and the thermal conductivity gradually increased,but the SEM of the material section showed that the internal structure could not form a directional thermal conduction channel.With the observation of the lyophilized internal structure of cellulose in SEM,and the thermal conductivity increased significantly,it proved that the thermal conduction path was successfully constructed.Finally,through PDA coating,the compatibility of BP/EP is higher than that of BN/EP.The one-pot method effectively loaded Ag particles on sulfhydryl modified BP,which effectively improved the thermal conductivity(λ_BP/EP=0.286 W/（m·K）at 20 wt%;At 20 wt%,λ_BPA/EP=0.318 W/（m·K）);When BPA and EP are blended and poured in the lyophilized skeleton,the thermal conductivity path containing filler can be seen in the cross-section,and the thermal conductivity of BPA/EP-Cλ_BPA/EP-C=0.361 W/（m·K）is twice that of EP thermal conductivity(λ_EP=0.176 W/（m·K）)when the filler amount reaches 20 wt%.At the same time,the impact resistance（Charpy）has been improved,and at 20 wt%load,C_BPA/EP-C=5.05 KJ/m² is 1.7 times that of C_EP=2.97 KJ/m².In the electrical properties of the composite,the dielectric constant of BPA/EP-C was 3.631,the dielectric loss was0.0197,the volume resistivity was 3.6×10¹⁴Ω·cm,and the breakdown field strength was8.79 k V/mm.This study provides a new idea for the structural design and fabrication process optimization of filled thermally conductive composites.