Research On Bionics Design?preparation And Properties Of Inorganic Sheet/aramid Nanofiber Thermal Conductive Composites

The high-speed development of the integrated circuit system has put forward higher demand for thermal management materials,of which flexible heat-conducting nanocomposites can be used in the field of thermal management of flexible electronic devices,electronic package materials,and flexible circuit boards,attracting concerns about many researchers.The flexible thermal conductivity nanocomposites are composed of thermal conductivity nano-fillers and polymer materials,which can achieve a high degree of integration of flexibility and functionality that is difficult to be achieved by traditional heat dissipation materials.Graphene and boron nitride are two-dimensional inorganic functional thermal conductivity fillers with excellent thermal conductivity,which are expected to be combined with various polymer materials to prepare flexible thermal conductivity polymer nanocomposites.However,it is still a huge challenge to prepare a composite material with excellent flexibility and high thermal conductivity by combining a high content of two-dimensional inorganic thermal conductivity nanosheets with a small amount of polymer.In this paper,we imitated the hierarchical layered architecture of mollusk nacre,and then design and prepare flexible thermal conductivity composite film with high two-dimensional inorganic thermal conductivity filler content(40%?70 wt%).Firstly,in order to solve the problem that the quality and yield of graphene are difficult to get at the same time.We developed a high concentration ball milling liquid phase stripping method to prepare graphene paste with a concentration of 50 mg m L^-1.Through the characterization test,it is proved that the GNS obtained has the advantages of fewer layers,high aspect ratio,few defects and high quality.Then,we prepare aramid nanofiber dispersion solution by deprotonation method.Finally,the graphene/aramid nanofiber composite film were prepared by sol-gel-film transformation approach by combining high quality and high concentration of graphene paste with aramid nanofiber.The composite film exhibits show nacre-like hierarchical layered composite structure.High-strength aramid nanofibers form a three-dimensional framework as matrix,which hosts 40 wt%?70 wt%oriented graphene platelets.Thanks to aramid nanofibers three-dimensional framework and?-?interactions,the composite film exhibits high mechanical properties,with the fracture strength of 179 MPa,modulus of 4.5 GPa,Strain-to-failure of 18.4%,and excellent thermal conductivity(91 W m^-1K^-1)and electrical conductivity(171 S m^-1).The boron nitride/aramid nanofiber composite film was prepared by sol-gel-film transformation approach.Thanks to the high interconnectivity of aramid nanofiber in the three-dimensional framework,the composite films have large ductility,up to 18.3-49.4%.Meanwhile,the composite films have high thermal conductivity(47.4-122.5 W m^-1K^-1)because high-loading boron nitride platelets form a percolative,oriented heat conduction path.Moreover,the outstanding ductility and thermal conductivity are integrated with high volume resistivity(10¹⁴-10¹⁶?cm)and thermal decomposition temperature(515?),enabling the structured boron nitride/aramid nanofiber composite film to be promising as flexible substrate for cooling electronic components.Finally,we extend the sol-gel-film transformation process to a continuous mode for fabricating boron nitride/aramid nanofiber composite film.