Preparation And Characteristics Of Polyimide/Nano-AMoO₄ Nanocomposites

Polyimide?PI?,as a high-performance polymer,has attracted increasing attention due to its high thermal stability,low dielectric constant,excellent mechanical properties and good chemical properties.However,with the size of VLSI reaching the deep sub-micron level,the traditional PI material can not fully meet the requirements of the development of the electronic device for excellent properties.Therefore,modification of PI has become a research hotspot.The molybdate nanoparticles possess both high strength,high rigidity and high stability of nano-particles,and high resistivity,high thermal stability and low dielectric loss of dielectric ceramic materials.Therefore,the modification of PI with molybdate nanoparticles is a novel and practical solution.In this study,thermosetting polyimide was modified by epoxy resins?EP?,Nano-BaMoO4 and Nano-MgMoO4.The surface treatment of nanoparticles was carried out by coupling agent KH550 and KH560 as surface active enhancers.And PI/EP/Nano-AMoO4 composites were prepared by ultrasonic blending.The effects of the introduction of molybdate nanoparticles on the morphology,thermal stability and dielectric properties of PI matrix were studied by means of SEM,XRD,FTIR,TGA and dielectric properties.And its internal mechanism was also studied.The SEM results of PI/EP/Nano-BaMoO4 composites material reveals that coupling agents KH550 and KH560 can uniformly disperse the nanoparticles in the PI matrix and enhance the compatibility of the nanoparticles with the PI matrix.The TGA shows that the thermostability of PI/EP/Nano-BaMoO4 composites is improved significantly from 518?to 623?and from 518?to 625?with the coupling agent KH550 and KH560 respectively.The measuring results of relative dielectric constant show that in the frequency range of 10^-1 kHz to 10² kHz,the relative permittivity of PI/EP/Nano-BaMoO4 composites decrease first and then increase with the increase of BaMoO4 nanoparticles.And the minimum value??=3.26?was reached at the content of 4 wt%.At high frequencies,the dielectric constant of the composites decreases first and then increases with the increasing frequency.The uniform design was also performed to investigate the effect of content of Nano-BaMoO4,KH550,EP on the dielectric properties of PI matrix composites.Calculating the regression equation based on the test results and testing the significance of the equation.The results show that the dielectric constant decreases first and increases later with the increase of Nano-BaMoO4content.This trend is consistent with the change of the dielectric constant obtained by the single factor experiment.The result of the automatic experiments shows that the optimum value of the experiment is obtained when MBaMoO4=2.52 wt%,MKH550=6wt%and MEP=65 wt%and the dielectric constant of the composites is 3.21.The PI/EP/Nano-MgMoO4 composites were also studied in the same way.The results show that PI/EP/Nano-MgMoO4 composites are similar to PI/EP/Nano-BaMoO4composites,which is a kind of composites with excellent thermal stability and dielectric properties.The above experimental study and test analysis shows that the modification of PI by nano-molybdate not only retained the excellent performance of original PI,but also improved the curing temperature,thermal stability and dielectric properties of PI.It laid the foundation for further research to improve performance of PI in the future.