关键词: 聚对亚苯基, LiNi_0.5Fe₂O₄, 纳米复合, 电导率, 热导率

Abstract: The microwave absorbing materials in future are characterized by thin thickness，light mass，wide range，strong absorption，and are required to endure high temperature，oceanic weather，nuclear radiation and so on.Polyparaphenylene and its derivatives，especially doped conducting polymer，might become a new kind of microwave absorbing materials owing to its easy preparation，good environmental stability and high microwave absorption.LiNi-ferrite powders could be used as microwave absorbers for X-band frequencies because of its high magnetic anistropic.The conducting polyaniline/LiNi-ferrite nanocomposites possess both dielectric losses and magnetic losses，so they have good application prospect in radar absorbing materials.Polyparaphenylene/LiNi-ferrite nanocomposites were prepared by a novel rheological phase reaction method.The effect of spark plasma sintering (SPS)conditions on electrical conductivity and thermal conductivity was investigated.The TEM images show the size of LiNi-ferrite is around 100-300 nm and the polyparaphenylene disperses in the oxide matrix evenly not only on the grain boundaries，but also inside the grains.It was found that the electrical conductivity of nanocomposites do not change with sintering conditions whereas the thermal conductivity increase with sintering conditions.With sintering times increasing，the size of LiNi-ferrite becomes large.The growing of LiNi-ferrite makes mean free path of phone and lattice thermal conductivity increase.The thermal conductivity increases with lattice thermal conductivity increasing.Because of the poor electrical conductivity of LiNi-ferrite，the growing of LiNi-ferrite has no effect on the electrical conductivity of nanocomposites.

Key words: polyparaphenylene, LiNi_0.5Fe₂O₄, nanocomposites, electrical conductivity；thermal conductivity