Preparation And Properties Of Nano - Al - Sub - 2 3 2 2 Modified Copolymer Polyimide Films

Polyimide film has outstanding thermal stability, mechanical properties and dielectric properties and is widely used in electronic field, automotive, aerospace and other fields. With the continuous progress of the science and technology, applications continue to be promoted, the performance requirements for polyimide film materials are also rising, especially the performance of the domestic polyimide film, obviously, can not catch up with the high performance of PI film abroad. Thus, to improve the performance of polyimide film is becoming the hotspot in our country.In this paper, nano-SiO₂ having good dispersion and release properties and nano-Al2O3 having outstanding high resistivity were chosen as the fillers, and their surface was modified. Copolyimide was chosen as matrix, respectively, with the methods of situ polymerization and blending, nano-SiO₂/Co-PI and nano-Al2O3/Co-PI composite film was prepared. The thermal firmness, mechanical properties, dielectric performance and other properties of the composite film are characterized.Experimental results show that, （1）with the craft parameters of the ndiamine:n dianhydride=1:1.015, noDA:np-PDA=7:3, the monomer solids content of 10%, the reaction time is 15h, the reaction temperature is 25℃ and the gradient temperature method, the thin film, having a good thermal stability and mechanical tensile properties, will be prepared. （2）with the method of APTES and improved APTES, nano-SiO₂ and nano-Al2O3, having a good dispersion, will be obtained. （3）whether situ polymerization method or direct blending method, It has good compatibility between nano-SiO₂/nano-Al2O3 particles and copolyimide substrate. （4）filling nano-SiO₂/nano-Al2O3 particles to polyimide film that makes the thermal stability decline, but the composite film still has a high thermal stability, decomposition temperature is above 528℃. （5）nano-SiO₂/Co-PI and nano-Al2O3/Co-PI composite membranes have better mechanical tensile properties and higher dielectric constant than pure film, the dielectric loss tangent shows respectively a decline and upward trend.