The Preparation And And Conductivity Stundy Of Cellulose Nanofibers/Polyaniline Composites

Cellulose is one of the largest biomass production in nature materials, becauseof its extensive sources, biodegradable, renewable and other characteristics，cellulose science has become a popular worldwide science. Currently, thedevelopment of cellulose science has been very wide,gradually developed into anintegrated science subjects intercross each other.In addition to the traditional papermaking,cellulose is also widely used and developed in textile industry, food,medical, chemical and so on.Polyaniline is a kind of typical conductive polymerswith many excellent properities,such as avariety structures, high conductivity, theunique mixed mechanism, excellent physical properties, good environmentalstability, and cheap, simple synthesis method, thus it becomes the leading missilepolymer research and research hot spot.In this paper, we use chemical and mechanical methods to process cellulosenano-fiber, and then prepared cellulose nano-fiber/polyaniline conductive compositeusing the situ polymerization method, which make aniline and cellulose as rawmaterial.In order to improve the conductive performance of composite materials, weadd to carbon nano-fibers, which obtained from cellulose nano-fibers carbonized athigh temperature. So we prepared the cellulose/polyaniline/carbon nano-fibersthree-phase composite materials.Finally we characterized and analyzed the samplesusing field emission scanning electron microscopy (sem), Fourier infraredspectrometer, universal mechanical testing machine, thermal mechanical analyzer,four point probe tester, X-ray diffractometer and other related equipment testingcomposite microstructure, chemical composition, mechanical properties, thermalproperties, electrical conductivity and related performance. The main conclusionsare as follows：(1)Using recycled paper as the main material, we use chemical treatment toremove the lignin and hemicellulose, then after grinding, ultrasonic, homogeneousphysical mechanical processing, we prepared cellulose nanofibers with nano-scale,high length-diameter ratio, high specific surface. Cellulose nano-fibers have wovenmesh structure, and each other of the suction filter cellulose film has excellenttensile strength and high elastic modulus and low thermal expansion.So they are anideal reinforcing material.(2) The mechanical performance of cellulose nano-fiber/polyaniline compositematerial,decreased with the increase of aniline content, but conductivity increasedwith increasing of the content of aniline.When the aniline content was30%,thecomposite has the highest conductivity. Composite material has good thermalexpansion properties, along with the increase in aniline content in the composite materials, thermal expansion coefficient are also increased.When aniline content was20%, the composite material has good conductivity, and maintained a certainmechanical properties.(3)By studying the factors affecting the conductivity of aniline and thesynthesis processes in the synthetic conditions, we concluded that the mixed acidand oxidant are the most important factors affecting the conductivity of aniline. Inthe synthesis processes of aniline adoping acid as acid increases, it indicated thatthe higher the acidity,the more the middle of the state in the process ofpolymerization,and the stronger the phase conductivity.But when the acidity reachedto a certain extent,aniline went on oxidate,thus intermediate substance transformatedinto oxidation state.At the same time,with the incresiung of concentration ofoxidizing agent,the more the content of intermediate substance at the processingof polymerization and the higher conducty.But when up to criticalpoint,the intermediate substance gradually transformed into oxidation state and theconductivity was decreased.Therefore, in the polymerization processing ofpolymerization,choosing the suitable acid and oxidizing agent was very important to theconducty of polyaniline,but should control their concentration.(4)The conductivity of the composite without carbon nano-fibers are generallyat10-3or10-2, but the conductive performance improved by2-3orders ofmagnitude with carbon nano-fiber, which as same as pure polyaniline conductivity.In composite material system, the network structure of cellulose nanofibers playeda role as the template,and it inhibited the reunion of polyaniline to some extent, andmake carbon nano-fibers and polyaniline fiber generate a conductive network usingthe network structure of cellulose.