Study On Microwave Absorption And Electromagnetic Shielding Efficiency Of Ag-loaded Cellulose

Electromagnetic interference has been a matter of increasing concern due to the rapid development of science and technology and the wide use of electronic equipment.Developing an effective EMI shielding material is an important way to solve EMI.Ag has good electrical conductivity,and Ag-loaded cellulose can not only obtain better EMI shielding efficiency,but also satisfy the thin and lightweight development of EMI shielding materials.1.In the system of TEMPO/NaBr/NaClO,cellulose primary alcohol hydroxyl group was selectively oxidized to form carboxyl group in aqueous solution.Combined with ultrasonic treatment,the size of cellulose was reduced and the dispersion of cellulose in aqueous solution was improved by the force between electric charges.When the dosage of NaClO was 4mmol/g,the stability of the cellulose water dispersion system was relatively good,and the absolute value of Zeta potential was 21.8.At the same time,the dispersion of cellulose in aqueous solution was improved after ultrasonic treatment,and the absolute value of Zeta potential reached 26.5(the Zeta potential of general stability state was 30).2.A thin coating layer of silver was prepared on cellulose nanofibers(CNFs)surface via electroless plating to obtain Ag/CNFs with pore structure on the surface.The process is simple,efficient and low-cost.The developed Ag/CNFs have a great advantage in electric conduction and microwave absorption.The identical deposit of thin silver layer was perfectly fabricated via the electroless plating on the CNFs surface.The average size of silver nanoparticles was 65 nm.The average pore diameter of Ag/CNFs was 32.59nm and the bet surface area was 1.89m2g-1.The fabricated Ag/CNFs were tested for electrical properties and electromagnetic attenuation.As a result,the resistance and conductivity of Ag/CNFs can reach 11.5 mQ and 636.9 S/cm.The total electromagnetic shielding efficiency can reach 24 dB.The reflection losses around 4.7 GHz,11.2 GHz and 15.6 GHz reach-51 dB,-46 dB and-41 dB respectively,and the corresponding absorption widths below-10dB were 2 GHz,3 GHz and 4 GHz respectively.3.A thin layer of silver was prepared on Cellulose film(CF)surface via electroless plating to obtain high Electromagnetic Shielding Effectiveness Ag/Cellulose composite layer.The process is simple,efficient and low-cost.The developed film has a great advantage in electric conduction and electromagnetic interference(EMI)shielding.The identical deposit of thin silver layer was perfectly fabricated via the electroless plating on the CF surface.The fabricated thin silver layers were tested for electrical properties and EMI SE.The elec al and electromagnetic shielding properties of the thin silver layer were ideal when activation concentration was 100 Mm(mmol/L).Herein,the resistance and conduct of Ag/Cellulose composite films can reach 0.35 ? and 45 s/cm,respectively,and MI SE of Ag/Cellulose composite films can be up to 67 dB ranging from 0.0003 GHz.The dielectric constant(?')of the Ag/Cellulose composite film was between 6.5 and 7.5,which was stable throughout the test band ranging from 2 to 18 GHz,The permeability(?')of the Ag/Cellulose composite film was around 1 ranging from 2 to 18 GHz.