介电导热云母/氮化硼纳米杂化聚酰亚胺薄膜的制备与性能研究

Preparation and Properties of Dielectric Conductive Mica/Boron Nitride Nanohybrid Polyimide Films

首先以六方氮化硼(h-BN)微粉及绢云母微粉(Mica)为原料,通过冻融循环结合超声工艺剥离出氮化硼纳米片(BNNS)及云母纳米片(MNS);之后以BNNS和MNS为绝缘导热填料,采用原位聚合法及二步法的水性聚酰亚胺(PI)工艺,制备了云母/氮化硼纳米杂化聚酰亚胺薄膜(简称为MNS/BNNS纳米杂化PI薄膜)。研究了不同MNS/BNNS填充量对纳米杂化PI薄膜性能的影响,采用XRD、TEM、AFM对BN、BNNS、Mica、MNS的形貌、结构进行了表征,并测定了MNS/BNNS纳米杂化PI薄膜的导热系数、介电常数及电气强度等性能。结果表明:当m(MNS)∶m(BNNS)=1∶2时,纳米杂化PI薄膜具有较好的综合性能,导热性能比纯PI大幅提高,导热系数为0.743 W/(m·K),电气强度可达246 MV/m,介电常数为5.28。

First of all,hexagonal boron nitride(h-BN)micro-powder and sericite micro-powder(Mica)were used as raw materials,boron nitride nanosheets(BNNSs)and mica nanosheets(MNS)were exfoliated by freeze-thaw cycle combined with ultrasonic technology.Then the BNNSs and MNS were used as insulating thermal conductive fillers,mica/boron nitride nanohybrid polyimide films(MNS/BNNS nanohybrid PI films)were prepared by in-situ polymerization and two-step water-based polyimide(PI)process.The influence of different MNS/BNNS filling amounts on the performance of PI composite films was studied.The morphology and structure of BN,BNNS,Mica,and MNS were characterized by XRD,TEM,and AFM,and the thermal conductivity,dielectric constant and electric strength of the MNS/BNNS nanohybrid PI films were measured.The results show that when the ratio between MNS and BNNSs is 1∶2,the MNS/BNNS nanohybrid PI films have better comprehensive properties,and the thermal conductivity is significantly improved compared with pure PI.The thermal conductivity is 0.743 W/(m·K),the electric strength is 246 MV/m,and the dielectric constant is 5.28.