Preparation And Characterization Of Polyimide Composites With High Thermal Conductivities

Polyimide has been widely used in electronic and electric industries because of its high thermal stability,low dielectric constant and excellent mechanical properties.With electron devices integrated and miniaturized,favourable thermal conductivity is required for electronic packaging materials as well as excellent electrical insulation property.Based on literature survey of thermally conductive polymer composites,three kinds of composites were prepared,using Graphite,Graphene,and hexagonal Boron Nitride(h-BN)as filler and Polyimide resin(PI)as polymer matrix,shown in the following three parts.(1)Preparation of PI composites with 3 kinds of platelet-shaped fillers and study on its thermal conductivityGraphite,Graphene,and h-BN were filled into PI to prepare three kinds of composites with high thermal conductivity,respectively,and the performance of the three composites was characterized for comparison.Among the three composites,the PI/Graphene composite with 40 wt% of Graphene loading shows the best thermal conductivity of 1.11 W/(m?K).On the other hand,the PI/BN system exhibits good insulation performance,the dielectric constant of the composite film being only 2.76 with 40wt% of h-BN loading.(2)Preparation of thermally conductive PI composites with different amounts of h-BNPI composites were prepared by filling different amounts of amino-BN contents,and the influence of amino-BN contents on thermal conductivity of the composites such as dielectric property and mechanical property etc were studied.With 40 wt% of animo-BN loading,thermal conductivity of the composites was of 0.73 W/(m?K),being 3.9 times of that for pure PI matrix.In addition,Nanodiamond and BN hybrid fillers were employed to improve the thermal conductivity furtherly.The composites consisting of 40wt% of ND and BN at the weight ratio of 1:10 showed the highest thermal conductivity,being up to 0.98 W/(m?K).(3)Covalent functionalization of h-BN with PCLThe h-BN was grafted with poly(?-caprolactone)(PCL)by two chemical covalent grafting methods,and the dispersibility of modified-BN in organic solvents was improved effectively.Since PCL is a kind of common biocompatible and biodegradable material,BN grafed with PCL may possess multipurpose applications in biomedical areas as biocompatible materials.