Study On Preparation And Properties Of PI/ Nano-AIN Hybird Films

In this paper, poly(amic acid) was synthesized by step-polycondensation of 4,4'-oxydianiline(ODA) and pyromellitic dianhydride(PMDA)in the solution of N,N-dimethylacetamide(DMAc). With the ultrasound-assisted, the silane coupling agent modified nano-AlN powder is added to the PAA by the way of high-speed sanding and mechanical blending .And then a number of hybrid films are made by thermal imidization method with different decentralized manner, different AlN content and different types of coupling agent.Sedimentation volume, lipophilic degree and surface hydroxyl groups of modified powder were characterized and tested. Properties of hybrid films including the morphology, thermal stability, mechanical properties, and electrical breakdown field strength were also characterized and tested. Scanning electron microscopy and UV-visible light transmittance analysis showed that the sanding method compared with mechanical stirring hybrid films prepared, AlN particle size is smaller and more uniform dispersion, and the thermal decomposition temperature, electric breakdown field strength and tensile strength are improved on, but the elongation at break decreased. The UV-visible light transmittance sharply decreased with the increase of AlN content of the hybrid films; thermal stability of the maximum value is 589oC at 6wt%, and then began to decline; In the beginning, hybrid films electric breakdown strength dcreased with the AlN content gradually increasing, but from 6wt% doped AlN the breakdown field strength gradually increased and began to decline once again when it reached 8wt%; it showed a continuous downward trend in the tensile strength and elongation at break. But the dielectric constant and dielectric loss took the upward trend. For different types of coupling agents KH550, KH560 and KH570, the best dosage were modified AlN powder mass 4wt%, 2wt% and 2wt%.The thermal stability, mechanical properties, electrical breakdown field strength and other properties are the best when a coupling agent KH550 4wt% is used, and the type of coupling agent loss has little effect on the ultraviolet- visible light transmittance, dielectric constant and dielectric.