Preparation Of Ni-Zn Ferrite/Polyaniline/Polyimide Porous Composite Film And Its Wave Adsorption Properties

With the development of economy and the rapid development of science and technology,it is extremely urgent to solve the electromagnetic radiation interference.All kinds of microwave absorbing materials with excellent performance have become the research focus in this field.Nickel-Zinc ferrite(Ni_xZn_（1-x）Fe₂O₄)is a kind of magnetic loss absorbent with excellent magnetic properties,but it has some problems such as high density and poor absorbent effect at high frequency.Polyaniline（PANI）is a dielectric loss absorbent,which can be used with magnetic loss absorbent such as nickel zinc ferrite to broaden the effective absorption band.Polyimide（PI）has attracted much attention and research due to its excellent thermal stability and mechanical properties,and can be used as matrix resin of high performance microwave absorbing materials.Based on the advantages of the above materials,this paper uses Ni-Zn ferrite/polyaniline composite filler as electromagnetic wave absorbing agent and polyimide as matrix to prepare Ni-Zn ferrite/polyaniline/polyimide（NPPI）ternary porous composite film by in-situ polymerization and thermally-induced phase separation technology,and explores its electromagnetic wave absorption properties.In this paper,Ni-Zn ferrite was prepared by hydrothermal synthesis method,and aniline monomer（An）was induced by in-situ polymerization on the surface of Ni-Zn ferrite.A series of Ni-Zn ferrite/polyaniline composite fillers were prepared by changing the mass ratio of Ni-Zn ferrite and aniline monomer.FT-IR,XRD,SEM,Raman,UV-vis,thermal performance test,electrical conductivity test and electromagnetic wave absorption test were used to characterize the structure morphology and properties of the prepared Ni-Zn ferrite/polyaniline composite filler.The results show that when the thickness is 2 mm and the frequency is 11.60 GHz,the absolute value of reflection loss（RL）of N_0.8Z_0.2F/PANI-20 wt%composite filler is 23.82 d B,and its effective absorption band width（RL<-10 d B）is 4.16 GHz.Using N_0.8Z_0.2F/PANI-20 wt%composite filler as electromagnetic wave absorbing agent,4,4’-diaminodiphenyl ether（ODA）,4,4’-（4,4’-isopropyl diphenoxy）diphthalic anhydride（BPADA）as monomers,dibutyl phthalate（DBP）as poreforming agent,in-situ polymerization and thermal phase separation technology,a series of NPPI porous composite films with different content of composite electromagnetic wave absorbent were prepared.The prepared NPPI was characterized by FT-IR,XRD,SEM,TGA,DSC,mechanical properties test,density test,hardness test,electrical conductivity test and electromagnetic wave absorption performance test.The microstructure and morphology analysis showed that the NPPI porous composite film was successfully prepared.The addition of composite filler had no obvious effect on the formation of imide ring and crystallization of polyimide,and the prepared NPPI had a porous structure and formed a network channel inside.Various performance tests and analyses show that NPPI porous composite film has good thermal stability and tensile properties.With the increase of composite packing content,the conductivity of NPPI increases,and NPPI has good dielectric loss and magnetic loss characteristics.When the composite packing content is 20 wt%,the absolute reflection loss of NPPI can reach 30.01 d B under the thickness of 4 mm,which has good electromagnetic wave absorbing performance.