Preparation And Properties Of Nanocellulose/Nano Silver Composite Film For Electromagnetic Shielding

The electronic communication technology developed rapidly and electromagnetic waves play an indispensable role in human society with the explosive development of science and technology.High power,miniaturization and high integration of electronic products are becoming increasingly.At the same time,the market demand for electromagnetic shielding materials has under gone rapid growth in recent years result from the electromagnetic radiation pollution is becoming serious.In this thesis,the films with excellent electromagnetic shielding performance have been prepared by couple cellulose nano fibers（CNF）with Ag nano particles（Ag NP_S）.The details are as follows:1.Used cellulose（CL）which extracted from larch pulp board to prepared the electroless Ag cellulose and CNF,the optimal process of electroless Ag cellulose was explored.The CNF was coupled with graphene and electroless Ag cellulose to prepared CNF/Graphene/electroless Ag cellulose composite film and the effect of electroless Ag cellulose on properties of CNF/Graphene composite films was investigated.The results showed that the surface roughness of electroless Ag cellulose was 3.10μm,and the conductivity was 935.80 S/cm,when concentration Ag NO₃was0.15 mol/L,the cellulose was 0.2 g,and the temperature was 40°C.A complete conductive network was formed inside the CNF/Graphene/electroless Ag cellulose composite film when added the 30wt%electroless Ag cellulose.The conductivity of the composite film increases from 0.68 S/cm to 3.8 S/cm,increasing by 458%,compared with no electroless Ag cellulose,and the electromagnetic shielding efficiency（SE_T）in the 0.03～3000 MHz was increased from 8.85 d B to 30.74 d B,increasing by 248%.2.CNF electroless Ag film was prepared by electroless Ag on CNF surface,and the effect of Ag NO₃ concentration on the properties of the composite film was researched.The results showed that the Ag particles with particle size of 18 nm on film surface distribution uniform and have good crystal structure,when the Ag NO₃concentration reached 0.125 mol/L.The SE_T of the composite film with roughness 4μm and contact angle 99°,was up to 34 d B in the frequency from 0.03 to 3000 MHz,the SE_A more than 30 d B.3.CNF/AgNP_S flexible composite films with excellent electromagnetic shielding effectiveness were prepared by mixing Ag NP_S dispersion with CNF dispersion.The results showed that Ag NPs with particle size of 33.4 nm and good crystallinity were immobilized on CNF surface uniformly by hydrogen bonding,when the CNF（M₁）:Ag NO₃（M₂）was up to 1:20.The cross section of the composite film has obvious hierarchical structure.The conductivity of film with a complete conductive network was up to 1184.16 S/cm.The SE_T of film with roughness 8.404μm and contact angle94°,was up to 80.7 d B in the frequency from 0.03 to 3000 MHz,and the SE_A was38.12 dB.