原位聚合法制备SiC@SiO2/BN/PI复合材料及其表征

聚酰亚胺复合材料以其优异的性能以及在航空航天、轨道交通、微电子等领域广泛的应用前景引起越来越多的关注。在750 ℃条件下对SiC晶须进行表面氧化处理, 形成SiC@SiO₂包覆结构晶须, 与BN颗粒构成复合填料, 分别采用硅烷偶联剂和钛酸酯偶联剂进行表面改性, 用原位聚合法制备了SiC@SiO₂/BN/PI(PI:聚酰亚胺)复合材料。采用傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)等进行结构和性能表征。结果表明: 晶须与颗粒质量比为4 : 1时, 复合填料在PI基体内形成了有效的导热网络, 且当填料含量为45wt%时, SiC@SiO₂/BN/PI复合材料导热系数达到0.95 W/(m·K)。SiC@SiO₂/BN/PI复合材料的力学性能随着复合填料的种类和数量的变化呈现规律性变化。SiO₂氧化层阻断复合填料间自由电子的移动, SiC@SiO₂/BN/PI复合材料的电气绝缘性能下降幅度减小。

Synthesis and Characterization of SiC@SiO2/BN/PI Composites by in-situ Polymerization

Polyimide composites have attracted more and more attention due to their excellent properties and wide application prospects in aerospace,rail transit,microelectronics and other fields.SiC@SiO2 whisker was prepared by oxidation of SiC whisker at 750℃,which formed mixed fillers with BN particles.The SiC@SiO2 whisker and BN were modified by a silane coupling agent and a titanate coupling agent,respectively.SiC@SiO2/BN/PI composites were prepared by in-situ polymerization.The structure and property of the fillers and composites were characterized.Whiskers and particles formed an effective pathway in the polyimide matrix,which promoted continuous improvement of the thermal conductivity of SiC@SiO2/BN/PI composites.When the total filler content was 45wt%and the mass ratio of whiskers to particles was 4:1,the thermal conductivity was increased to 0.95 W/(m·K).Mechanical properties of SiC@SiO2/BN/PI composites changed regularly with the type and amount of mixed fillers.The SiO2 layer blocks the communication of free electrons between the mixed fillers,and the decreasing range of electrical insulation performance of the SiC@SiO2/BN/PI composites declined.