| In the information age,the massive various high-power electronic devices has been used,which caused mass electromagnetic waves.The disorderly propagation and flooding of electromagnetic waves has resulted in electromagnetic pollution.Electromagnetic pollution has been listed as the fourth largest source of pollution.Excessive electromagnetic pollution may cause a series of problems related to human health,information security,and environmental issues.Electromagnetic shielding materials have received widespread attention because they can effectively protect the human body and equipment from electromagnetic interference.The preparation of electromagnetic shielding materials is mostly based on metals,carbon materials and conductive polymers.Our country has also made certain achievements in the field of electromagnetic shielding.However,electromagnetic shielding materials have limited their development due to factors such as resources,processing conditions and performance.Because cellulose has a wide range of sources,low price,abundant output,good flexibility,long fibers and stable dimensions,its use to prepare electromagnetic shielding materials is a new direction for preventing electromagnetic pollution and a new direction for cellulose resource utilization.In order to prepare light-weight,inexpensive,and good-shielding electromagnetic shielding materials,the paper surface with cedar cellulose paper was metalized in electroless Ni plating technology.The specific research content of shielding paper is as follows:(1)Water/ethanol was used as solvent system for APTES,the best conditions based on the mass change rate of cellulose paper are as follows:volume concentration of 2.0%APTES,water content of 50 g/L,and aging time for 5 h.SEM observed that the surface of the cellulose paper is relatively smooth when it was treated with APTES.The modified cellulose paper adsorbed Pd2+through complexation.Pd2+is reduced to Pd by NaH2PO2 and firmly adhered to the surface of the cellulose paper.The electromagnetic shielding material was obtained after chemical plating reaction.The electromagnetic shielding material has good thermal stability and electromagnetic shielding performance.The surface resistance is 180.8 m?/sq after 30 minutes of plating,and the shielding effectiveness can reach 70 dB.XRD result showed that the Ni-P coating on the surface of the fiber paper presents a crystalline structure.On the surface of Ni/cellulose paper,a dense and continuous coating structure with metallic luster was observed.(2)The NaBH4/NaOH was used as activator to activate the surface of cellulose paper.The best activation conditions are:NaBH4 concentration is 3 g/L,NaOH concentration is 3 g/L,and activation time is 2 min.The activated cellulose paper was electrolessly plated with 40 mL of plating solution and pH=9 for 30 minutes to obtain an electromagnetic shielding material with a surface resistivity of 4.67 ? cm-2.SEM observed that the electromagnetic shielding material has a unique laminated felt-like structure.The thickness of the electromagnetic shielding material reached to 4.36 mm,and the test showed excellent shielding effectiveness in the range of 9 kHz to 1.5 GHz,and shielding effectiveness is 65 dB.At the same time,TGA technology showed that electroless Ni plating technology helped to change the thermal stability of cellulose.(3)In order to further improve electromagnetic shielding materials of the absorption loss of electromagnetic wave,on the basis of NaBH4/NaOH as activator,0.15 g/L MWCNT-COOH was added to the plating solution to prepare Ni-P-MWCNT electromagnetic shielding material with good absorbing properties.The surface resistance is 186 m?/sq.SEM was observed the structure of short rod-shaped MWCNT on the surface of the coating.XRD result showed that MWCNT affects the cell structure of the nanocomposite coating. |
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