超支化聚合物修饰氮化硼微球/环氧树脂导热复合材料的制备及性能

Preparation and Properties of Thermally Conductive Epoxy Composites Based on Hyperbranched Polymer-Modified Boron Nitride Microspheres

选择粒径30μm和120μm的氮化硼微球(GBN)作为导热填料,通过超支化环氧树脂(HPEP)与GBN之间的π-π相互作用得到了超支化聚合物修饰的氮化硼微球(HPEP-GBN),通过共混制备了具有不同复配比例的环氧树脂复合材料(HPEP-GBN/EP)。调整小粒径填料的质量分数(Xs)研究了不同氮化硼微球的复配比例对复合材料流变行为和导热性能的影响,进一步分析了填料的形状和超支化聚合物的表面修饰对复合材料性能的影响。结果表明,当Xs=0.4时,HPEP-GBN/EP复合材料的黏度最低,具有比GBN/EP复合材料更优异的加工性能和导热性能。体系的填料质量分数可以达到80%,此时导热系数达到了5.28W/(m·K),是纯环氧树脂的31.06倍。此外,HPEP-GBN/EP复合材料还具有比GBN/EP更优异的力学性能和热稳定性、更低的介电损耗和热膨胀系数。

Boron nitride microspheres(GBN)with the particle size of 30μm and 120μm were selected as thermally conductive fillers,and hyperbranched polymer-modified boron nitride microspheres(HPEP-GBN)were then prepared throughπ-πinteraction between hyperbranched epoxy(HPEP)and GBN.Then epoxy composites(HPEP-GBN/EP)with different compounding ratios were prepared by a simple blending process.By adjusting the mass fraction of small size GBN(Xs),the influence of the appropriate Xs ratio,the shape of GBN and surface modification on the properties of the epoxy composites were investigated.The results show that,when Xs is 0.4,the HPEP-GBN/EP has the lowest viscosity.The HPEP-GBN/EP composites have a better processability,as well as a higher thermal conductivity than the GBN/EP composites.The filler addition amount of the epoxy composited system could reach to 80%,at this time,the thermal conductivity coefficient of HPEP-GBN/EP composite reaches 5.28 W/(m·K),which is~30 times higher than that of neat EP.In addition,HPEP-GBN/EP composites also exhibit better mechanical properties,thermal stability,lower dielectric loss and thermal expansion coefficient.