| Electronic equipment is gradually developing towards high performance,high-integrated,and lightweight.Notably,the chips and equipment used the 5G era are in urgent need of high insulating dielectric materials with low cost,high thermal conductivity???,and low dielectric loss.In order to comply with the demand,researches on the thermally conductive insulating composites became the necessary and critical process to solve heat dissipation problems.Because of its excellent electrical insulation,prominent thermostability,superior processability and mechanical properties,Nylon 6?PA6?resin has numerous applications,such as electronic equipment,packaging materials,and insulating substrates.However,due to the poor performance on the thermal conductivity of pure PA6 is limited in heat dissipation.Boron Nitride?BN?with low cost and excellent performance is a two-dimensional sheet material similar to Graphene?GNP?,and also one of the hottest thermal conductive fillers.In the current research about Polymer-based composites with high thermal conductivity,BN and GNP of two-dimensional sheet materials are mainly filled into polymers.The BN has gradually been favored by researchers due to its outstanding electrical insulation and light color.The BN is directly compounded with polymer through conventional direct blending approaches to realize high heat conduction,which will bring some inevitable challenges.For example,excessive addition could seriously deteriorate the excellent mechanical and other comprehensive properties of the polymer itself.On the other hand,the addition of very small amounts could cause the filler to be wrapped by polymer and could not form consecutive thermal conductive paths.Therefore,how to balance thermally conductive and other properties,to develop a kind of composite with high?and excellent mechanical properties at a low filler loading for thermal management applications has become a research focus.In this paper,the Cast Nylon 6?PA6?prepared by mature anionic ring-opening polymerization.It is the aim of the present work to develop three kinds of novel Nylon 6/Boron Nitride?PA6/BN?composites with high?prepared by using in situ polymerization,hexagonal Boron Nitride?h-BN?and caprolactam?CL?as primary raw materials.The main conclusions of the research are as follows:?1?Hydroxyl groups were grafted on the surface of h-BN by hydrothermal reaction,and then isocyanate-functionalized Boron Nitride?BN-NCO or f-BN,for short?was further prepared.The PA6 composites based on h-BN and f-BN were prepared according to the“grafting from”respectively.The effects of the PA6/f-BN and PA6/h-BN composites systems were then investigated on their thermal properties,morphological structure and mechanical properties.Thermal conductivity of PA6/f-BN composites was improved to 0.50 Wm-1K-1with 5 wt%f-BN loading and was enhanced by 28.0%to PA6/h-BN composite and 66.7%to neat PA6.It can be found that,with 5 wt%f-BN loading,the Young's modulus is gradually increased from 914 MPa for PA6 to as high as 1224 MPa for PA6/f-BN and the yield strength from 46.9 MPa to 61.8 MPa,which are improved by 33.9%and 31.8%,respectively.Both?and mechanical properties of PA6/f-BN composites enhanced slightly at a relatively low amout of fillers.It could be attributed to the formation of BN-grafting-PA6?BN-g-PA6?which significantly improves the interfacial bonding between PA6 and BN in the matrix of PA6,and then reducing thermal resistance.The latter products could be considered as compatibilizer as well.Meanwhile the enhancement function of BN was sufficiently reflected.?2?The h-BN and inorganic compounds were used as thermally conductive fillers and dispersant respectively.The highly ordered three dimensional Boron Nitride?3D-BN?scaffolds were prepared through using the ice-templating method to control the freezing direction and combing sintering technology.After vacuum infiltration technology,monomer filled to porous3D-BN scaffolds to obtain complete PA6/3D-BN composites.For comparison,PA6/h-BN composites with the same BN content were prepared via melt blending,in which 3D-BN scaffold was replaced by h-BN.The results indicated that the?of composites were increasing with the increment of filler for any one of the preparation method.The ordered 3D-BN scaffolds structure favored the formation of the consecutive thermal conductive paths even a relatively low BN loading.Moreover,due to the porous and lightweight structure,a large amount of PA6 phase could be filled in the gaps to realize high?.At the highest loading 26wt%,?values in the parallel and perpendicular directions for the PA6/3D-BN composites reach 2.11 Wm-1K-1and1.44 Wm-1K-1,respectively,whereas the?of pure PA6 was only 0.30 Wm-1K-1.The?of PA6/h-BN composites also have obvious superiority by preparing the melting blending method.The highest values respectively increased by 154%and 73%than that of PA6/h-BN composites at the same content amout of h-BN,respectively.The thermal stability of PA6/3D-BN composites was improved due to the action of 3D-BN scaffolds.?3?The porous 3D-BN/GNP scaffolds with the same procedure were prepared by introducing a small amount of GNP,and then PA6/3D-BN/GNP composites were obtained by in-situ polymerization.The GNP was introduced to achieve equivalent?at a low filler loading.The results indicated that the introduction of the GNP had no significant side effects on other properties of the PA6/3D-BN/GNP composites.At the highest loading 26wt%?23.4 wt%h-BN:2.6 wt%GNP?,?values in the parallel and perpendicular directions for the PA6/3D-BN/GNP composites reach 2.80 Wm-1K-1and 2.23 Wm-1K-1,respectively.The?of pure PA6 was only 0.3 Wm-1K-1.The?of PA6/3D-BN/GNP composites is enhanced by 33%to the parallel direction and 55%to the perpendicular direction.The introduction of GNP and h-BN has a synergistic effect for enhancing?in the PA6 composites.This result of thermal infrared imaging illustrated that the PA6/3D-BNr composites and PA6/3D-BN/GNP composites had much better heat absorption and dissipation,which was in good agreement with the results of the thermal conductivity. |
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