Preparation And Electromagnetic Shielding Properties Of Polyarylene Ether Nitrile/Carbon Fiber Complexes

The widespread use of electronic devices and microwave technology has led to serious electromagnetic radiation pollution,and it is crucial to develop EMI shielding materials with excellent performance.Polymers are considered to be the best matrix for manufacturing EMI shielding composites due to their light weight,toughness,flexibility,corrosion resistance,and ease of processing.As a special engineering polymer,polyarylene ether nitrile has outstanding thermal properties,mechanical properties and flexible molecular designability.In this thesis,alternating multi-layered polyarylene ether nitrile/carbon fiber cloth composites with good overall performance are designed and prepared by combining the inherent advantages of polyarylene ether nitrile and functional fillers through a reasonable design and compounding process,using a non-solventogenic phase separation preparation technique.The effects of different nano-fillers on the performance of the composites are investigated,and the advantages and mechanisms of composite materials in electromagnetic shielding applications are also explore.Firstly,the polyarylene ether nitrile/Fe₃O₄/carbon fiber cloth composites are prepared by assembling layers of carbon fiber cloth with cyano-capped polyarylene ether nitrile（PEN-t-Ph）.PEN-t-Ph is used as the polymer matrix and functionalized Fe₃O₄@PEI nanoparticles as the filler.When the number of carbon fiber cloth layers in the material reached three layers and the mass fraction of Fe₃O₄@PEI is 25%,the material exhibit suitable conductivity（1.63 S/cm）and good saturation magnetization strength（1.99 emu/cm³）,The EMI SE_T and specific shielding effectiveness SSE/t is up to 37.76d B and 505 d B·cm²·g^-1,respectively.The prepared composite materials own the absorption-dominated EMI shielding characteristic.In addition,the material has the characteristics of light weight（ρ=0.55 g/cm³）and good mechanical properties（tensile strength=26.59 MPa）.Next,PEN/MWCNTs/carbon fiber fabric composites are prepared by assembling layers of carbon fiber cloth.The multi-walled carbon nanotubes（MWCNTs）are functionalized with dopamine（DA）and KH550 is as the fillers.When the number of carbon fiber fabric layers in the material reach three layers and the mass fraction of PKMWCNTs in composite materials is 50%,the material exhibited suitable electrical conductivity（1.95 S/cm）,high EMI SE_T（39.97 d B）and specific shielding effectiveness SSE/t(549 d B·cm²·g^-1).The prepared composite materials own the absorption-dominated EMI shielding characteristic.In addition,the material has the characteristics of light weight（ρ=0.55 g/cm³）and good mechanical properties（tensile strength=43.72 MPa）.Finally,Fe₃O₄ is in situ grown on carboxylated carbon nanotubes（MWCNT-COOH）by co-precipitation method,and the alternating multilayer material is successfully prepared by consist of CFC and the carbon nanotubes fillers that is functionalizing with dopamine（DA）and KH550.When the number of carbon fiber cloth layers in the material reached three layers and the mass fraction of PKMWCNT@Fe₃O₄ is 50%,the material exhibited suitable conductivity（1.90 S/cm）and good saturation magnetization strength（1.37 emu/cm³）.The EMI SE_T and specific shielding effectiveness SSE/t can be up to47.08 d B and 617 d B·cm²·g^-1,respectively,and the EMI shielding mechanism of composite is absorption-dominated type.Moreover,the composite show light weight（ρ=0.55 g/cm³）and good mechanical properties（tensile strength=43.98 MPa）.This work presents a new approach to preparing high-performance composites with lightweight and is resistant to secondary contamination of electromagnetic waves.