| The electromagnetic pollution is becoming more and more serious because of the increasing popularity of electronic products.The research and development of electromagnetic shielding fabrics has gradually become one of the highlights of people's attention.The metal fiber with excellent mechanical properties and good electrical conductivity has been widely used in signal transmission,anti-static and electromagnetic shielding fields.In addition,core-shell structured nanoparticles have become one of the research hotspots in the fields of nanomaterials due to the multiple composite properties of mixing multi-component particles.This research combines core-shell nanomaterials with metal fiber fabrics to prepare nanocomposite fabrics with electromagnetic shielding function.The main research contents are as follows.(1)Preparation of Fe3O4@Zn O core-shell structured nanoparticlesThe Fe3O4@Zn O core-shell structure nanoparticles were prepared using solvothermal and sol-gel methods.The product was characterized by SEM,TEM,HRTEM,FT-IR,XRD,EDS and DLS.The electrical and magnetic properties of the product was tested by the semiconductor parameter test system,VSM and permeability meter,respectively.The results show that the prepared nanoparticles have a shape of microsphere structure.The diameter of most particles of Fe3O4 microspheres in the core is 413.5 nm,and its saturation magnetization is 79.93 emu·g-1.The remanence and coercivity are as low as 1.59 emu·g-1and 17.01 Oe,respectively,and the product has good soft magnetic properties.With an increase in the thickness of the Zn O shell,the saturation magnetization of the nanoparticles decreased from 62.38 emu·g-1to 23.30 emu·g-1,and the relative permeability decreased from 1.142 H·m-1to 1.087 H·m-1.However,the conductivity value increased from3.54×10-7 S to 16.9×10-7S.(2)Preparation of aramid/stainless steel fiber blended fabricAramid/stainless steel fiber blended yarn was used to prepare woven fabric.The effect of yarn blending ratio,structure and warp/weft density on the electromagnetic shielding performance of the fabric was studied,and its comprehensive performance was tested.The results show that with an increase in stainless steel fiber content,the shielding effectiveness(SE)of the fabric reaches up to 50 d B.Among the three original structures,the plain weave fabric has the best shielding performance.The shielding performance increase with the warp/weft density of the fabric increased.In addition,the flame retardant performance of the fabric meets the B1 assessment standard of flame retardant protective clothing fabrics.The fabric has good tensile properties,and the breaking strength is as high as 2 030 N.Its washing resistance is excellent.After 20 times of soaping,the SE value of the fabric only drops by 3 d B at most.The color fastness and staining fastness are up to 4-5grades.(3)Preparation of aramid/stainless steel fiber-based core-shell nanocomposite fabricThe aramid/stainless steel fiber fabric is used as the base fabric and the core-shell structure Fe3O4@Zn O is used as the functional body to prepare a composite fabric with electromagnetic shielding performance.The dispersion stability of coating size,and the effect of nanoparticle content,Zn O shell thickness and coating thickness on the electromagnetic shielding properties of composite fabrics were studied.The results show that the coating size has good dispersibility.No precipitation occurs after standing for 15minutes,and it can be evenly dispersed on the surface of the fabric after coating.The SE value of the composite fabric can reach more than 40 d B in the low frequency band(0.3?100 MHz),which meets the standard of general technical conditions for industrial electromagnetic shielding fabrics.As the content of nanoparticles is increased,the shielding performance of the composite fabric improved,and its SE value can reach 48 d B.With an increase in the thickness of the Zn O shell,the shielding effectiveness of the fabric in the low-frequency range is slightly reduced,while improved in the high-frequency range.When the test frequency is less than 2 200 MHz,the SE value of the composite fabric increases with the coating thickness.When the frequency is more than 2 200 MHz,the SE value decreased.The composite fabric has good flame retardant properties.Its tensile properties have been improved.It has good washing resistance.However,the air permeability has been reduced.This paper clarified the mechanism of the influence of core-shell structured nanoparticles on the electromagnetic shielding performance of aramid/stainless steel fiber blended fabric.The composite of aramid/stainless steel fiber blended fabric and core-shell structured nano-functional body has been realized,and the shielding performance of fabric in the low frequency range has been improved.This paper provides theoretical basis and practical guidance for the development and engineering application of electromagnetic shielding materials. |
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