Preparation And Electromagnetic Shielding Effectiveness Study Of Cellulose/PANI Conductive Composite

With the continuous development of electronics and information technology,the human body is inevitably exposed to the complex electromagnetic environment.A large number of studies have shown that electromagnetic radiation can induce a variety of biological effects and have potential hazard to human health.For this reason,research and development of electromagnetic shielding materials have become the focus of attention.The current electromagnetic shielding materials are mainly metal conductive composite fabrics.The fabrics have good electromagnetic shielding effectiveness,but they have high costs and complicated preparation technique.Nowadays,the development and application of conductive polymer materials provide a new idea for preparing lightweight,low-cost and stable electromagnetic shielding materials.In the study,the porous structure of regenerated cellulose membranes was used as a microreactor,polyaniline(PANI),a conjugated conductive polymer,was composited into cellulose matrix by in-situ polymerization to study the electromagnetic shielding effectiveness,mechanical properties and biocompatibility of Cellulose/PANI membranes,The study lays the foundation of the subsequent production of Cellulose/PANI fabrics by utilizing the fibrillar spinnability of cellulose.Cellulose membranes with different cellulose mass fraction were prepared by lowtemperature solubilization of LiOH/Urea solutions in the experiment.The specific surface area of cellulose membranes was measured by physical adsorption instrument.The surface and cross section of cellulose membranes were observed by scanning electron microscope.Using the prepared porous cellulose membranes as microreactor,aniline with different concentration were polymerized to celluloses membranes to prepare Cellulose/PANI by in-situ polymerization.The influence of cellulose mass fraction and aniline concentration on the electromagnetic shielding effectiveness,mechanical properties and biocompatibility of Cellulose/PANI were investigated.FTIR(Fourier transform infrared spectroscopy)was used to characterize the structure of Cellulose/PANI.The conductivity of membranes were measured by four-point probe instrument.Dielectric parameters of membranes were measured using an impedance analyzer.The lossy medium model was established to theoretically calculate the electromagnetic shielding effectiveness of membranes using the obtained electromagnetic parameter,and the electromagnetic shielding mechanism was further analyzed.Universal test stretching machine was used to measure the mechanical properties of membranes.Biocompatibility of membranes were detected using LDH cytotoxicity experiment.The results showed that:1.Cellulose membranes obtained by the low-temperature dissolution of cellulose wool fluff pulp in LiOH/urea dissolving system have stable structure,fine mechanical property and biocompatibility,and have continuous distribution of mesh structure,it's suited to be the microreactor of in-situ polymerization of aniline.PANI formed by in-situ polymerization of aniline existed in the cellulose net structure and developed a nested composite structure together with cellulose.2.The Cellulose/PANI membrane has good conductivity,and its carriers are mainly holes.When the concentration of aniline is 1 mol/L and the mass fraction of cellulose is in the range of 2 wt%~5 wt%,the conductivity of membranes is between 0.01 and 0.06 S/cm,and the conductivity decreases with the increase of cellulose mass fraction.When the mass fraction of cellulose is 4 wt% and the concentration of aniline is in the range of 0.25 ~ 1.5 mol/L,the conductivity of the membranes is between 0.00069 and 0.1175 S/cm,which increases with the increase of aniline concentration.3.The Cellulose/PANI membranes has both reflection and absorption loss of electromagnetic waves,and its shielding effectiveness decreased with the increase of the electromagnetic wave frequency.At the same concentration of ailine,the shielding effectiveness of membrane is affected by the mass fraction of cellulose,with the increase of the mass fraction of cellulose,the shielding effectiveness decreased.When the mass fraction of cellulose is fixed,the higher concentration of aniline,the higher shielding effectiveness of Cellulose/PANI membrane.4.The mechanical properties of Cellulose/PANI membranes are mainly determined by the mass fraction of cellulose.The greater mass fraction,the better mechanical properties of the membrane.PANI has some influence on mechanical properties of membranes,this effect is significant when the cellulose mass fraction is low(2 wt%),but when the cellulose mass fraction is high(4 wt%,5 wt%),the effect is not obvious.5.Cellulose/PANI membranes had no significant acute cytotoxicity.Considering the effects of cellulose mass fraction and aniline concentration with different proportions on the electromagnetic shielding effectiveness and mechanical properties of Cellulose/PANI membranes,Cellulose/PANI membrane prepared with 4 wt% cellulose membrane and 1.5 mol/L aniline has the best overall performance.