High Thermal Conductivity Filler To Enhance The Thermal Conductivity Of Polymer Materials

With the miniaturization of electronic packaging technology,electronic chips and many other technologies,the heat dissipation requirements of electronic devices are becoming higher and higher.Polymer composites have the advantages of simple process,light weight and good chemical resistance,which are adopted in thermal management.However,the thermal conductivity of the polymer material itself is not high,so the search for ways to improve the thermal conductivity of the polymer material is becoming more and more important,and the number of studies on this topic is increasing.More and more studies have shown that constructing a two-dimensional network structure,three-dimensional composite skeleton,and adding high thermal conductive fillers are effective ways to improve the thermal conductivity of polymer composites.In this study,we deposited nanocrystalline diamond grains on the surface of silicon carbide particles by hot filament chemical vapor deposition and prepared a novel barnacle-like structure as a filler and a polymer composite material with a novel hybrid structure using PVDF polymers as a matrix.1.The main process parameters of hot wire CVD equipment are:methane/hydrogen concentration ratio,hot wire pitch,power of hot wire equipment and deposition time.We investigate the process of depositing nanocrystalline diamond on a substrate of silicon carbide particles by changing one parameter of the hot-wire chemical vapor deposition equipment at a time,while keeping the other parameters constant.Observation of the substances deposited on the surface of silicon carbide particles by scanning electron microscopy(SEM)and their Raman spectroscopic analysis.We finally determined the process required for the preparation of the final filler at 5%CH4 concentration,4 hot filaments with an average power of 1000 W per strand,a distance of 7.5 mm from the hot filaments to the surface of the deposited substrate,and two deposition times of 3 h respectively.2.Through the SEM image of the new barnacle-like structure filler prepared by the optimal process for particle size statistics,we found that the average size of silicon carbide particles used is 11.2 ?m,and the average size of diamond particles deposited is 0.5 ?m.After cutting the filler by focusing ion beam and analyzing it under transmission electron microscope,we found that the 0.256 nm crystal plane spacing of silicon carbide particles and 0.206 nm crystal plane spacing of diamond were consistent with those of silicon carbide and nanocrystalline diamond.Raman spectra of barnacle packing further revealed the crystallinity and strength of diamond deposited.We can clearly see the characteristic peak of diamond at 1140 cm-1,the D peak of carbon material at 1332 cm-1 formed by sp3 hybridization and the G peak of carbon material at 1580 cm-1 for1ed by sp2 hybridization on Raman spectrum.The TGA-FTIR analysis of the filler showed that the mass lost at 750? was caused by the oxidation of the deposited diamond to carbon dioxide,so 9.22%mass lost was the mass of the new type filler occupied by diamond.3.DMF was used as the solvent to disperse and mix PVDF base and packing.After rotating and steaming the solvent,the obtained solute was hot-pressed to obtain the final polymer composite material.We can know that the thermal conductivity of the composite increases with the increase of the filler content.The thermal conductivity of ND@SiC/PVDF composite material containing 70 wt.%barnacle structure filler was 2.39w m-1 K-1,which increased by 1132%compared with pure polymer material.The thermal conductivity of SiC/PVDF composite with the same packing content is 1.48w m-1 K-1,which is not as good as the polymer composite prepared by new barnacle-like structure filler.The pure polymer material,SiC/PVDF polymer composite material and ND@SIC/PVDF composite material were heated at the same time,and their surface temperature was measured by infrared thermography.It can be found that ND@SiC/PVDF composite material has the fastest heating rate and the highest temperature achieved after the same period.This work also provides a new idea for the preparation of heat-conducting polymer composites of diamond packing,and provides a new possibility for improving the thermal conductivity of heat-dissipating materials in advanced packaging materials.