Preparation And Properties Of Functionalized Boron Nitride Nanosheets/Epoxy Resin Thermal Conductive Composites

With the development of integration and miniaturization of electronic technology,efficient heat dissipation of electronic equipment has become a bottleneck in the development of this field.Thermal conductive epoxy composites are the important materials to solve the heat dissipation.Non-covalent methods are adopted to modify the surface of boron nitride nanosheets?BNNs?in this thesis.Then epoxy composites with high thermal conductivity were prepared and characterized using functionalized BNNs as fillers.The effects of surface functionalization on the microstructure and thermal conductivity of composites were investigated in detail.The mechanism of BNNs surface modification to improve the thermal conductivity of composites was explored by therotical calculation.The main contents are as follows:?1?The surface of BNNs were modified with tannic acid-Fe ions complexes?TA@Fe?,4-phenylbutylamine?PLM?and tannic acid/4,4-diaminodiphenylmethane?TA@DDM?to obtain functionalized boron nitride nanosheets?TA@Fe-BNNs,PLM-BNNs and TA@DDM-BNNs?,respectively.The results of FT-IR and EDS confirm that BNNs were successfully functionalized.The results of TEM and SEM show that the lattice structure of BNNs remained unchanged before and after functionalization.?2?TA@Fe-BNNs,PLM-BNNs and TA@DDM-BNNs as fillers were incorporated into epoxy by directly blending to fabricate epoxy nanocomposites?TA@Fe-BNNs/EP,PLM-BNNs/EP and TA@DDM-BNNs/EP?,respectivley.SEM and DSC show that TA@Fe,PLM and TA@DDM modification can effectively improve the dispersion of BNNs in EP,and enhance the BNNs-EP interfacial compatibility.The results of thermal conductivity test indicate that the three modification methods can effectively improve the effect that BNNs enhance the thermal conductivity of EP.The thermal conductivity of the compositess follows in turn:TA@Fe-BNNs/EP<PLM-BNNs/EP<TA@DDM-BNNs/EP,indicating that the TA@DDM-BNNs haved the highest thermal conductivity.When the filling amount is 30wt%,the thermal conductivity of TA@DDM-BNNs is 0.887 W/m·K,which is 303.4%higher than that of pure EP.?3?The Y.Agari and Foygel models are applied to analyze the thermal conductivity of the composites.And the thermal network factor C₂ and the interface thermal resistances R_kwere calculated.The functionalization of BNNs can largely increase the C₂?an increase of more than 85%?and reduce R_k?a decrease of more than 34%?.As a result,the functionalized BNNs/EP composite shows better thermal conductivity.Among them,TA@Fe modification has the maximum increase in C₂,and PLM and TA@DDM modifications have the most significant reduction in R_k.TA@DDM modification can not only improve C₂ significantly but also reduce R_k at utmost.It is reasonable that TA@DDM-BNNs/EP show the best thermal conductivity.