Preparation and Properties of Heat-Conducting Epoxy Resins Based on the Oriented Magnetic Boron Nitride
To improve the thermal conductivity of epoxy resin(EP)while maintaining its original properties at a low heat-conducting filler content,magnetic boron nitride nanosheets(mBNNSs)were prepared by introducing magnetic ferric oxide(Fe3O4)particles onto boron nitride nanosheets(BNNSs)through a coprecipitation method.Under the external magnetic field,heat-conducting epoxy resin(mBNNSs-EP)composite materials were prepared by using EP as the matrix and mBNNSs as the filler.The structures,magnetic responsiveness,and orientation of mBNNSs in EP,along with the cross-sectional morphologies,heat-conducting,thermal stability,insulation,and mechanical properties of mBNNSs-EP composite materials,were analyzed and characterized.X-ray powder diffraction(XRD)and scanning electron microscope(SEM)results respectively confirm the synthesis of Fe3O4 on the surface of BNNSs and the good orientation of mBNNSs in EP.Compared with EP,the thermal conductivity of the mBNNSs-EP composite materials rises as the mBNNSs content increases.The thermal conductivity of 20％-mBNNSs-EP composite material is the highest,reaching 1.239 W/(m·K).The heat decomposition temperature of mBNNSs-EP composite material exceeds 303℃,the glass transition temperature(Tg)is over 130℃,and the bending strength is over 56.93 MPa,indicating that this mBNNSs-EP composite material has good thermal stability and mechanical properties.The vertical orientation of mBNNSs in EP significantly enhances the thermal conductivity of mBNNSs-EP composite material,and mBNNSs-EP composites basically maintain other properties of EP.
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