Study On Thermoelectric Performance Of Polyaniline And Its Composites

Thermoelectric(TE)materials refer to a series of materials which can achieve direct conversion of thermal and electrical energies.Thermoelectric materials have broad applications in thermoelectric generation and refrigeration technologies.Inorganic thermoelectric materials with good performance are mature relatively,but which are expensive and difficult to be machined.Being a typical conductive polymer,the polyaniline(PANI)has many advantages(i.e.prepared easily,inexpensive,good stability,unique doping mechanism and low thermal conductivity),and which has been concerned as a potential and low-cost polymer based thermoelectric material.However,the thermoelectric properties of PANI are very low comparing with the traditional thermoelectric materials.In this investigation,polyaniline and its composites were prepared and the TE properties of which were studied by the ZEM-3,LFA-457,SEM,and aome other equipments.Main contents of this investigation are shown as follows:(1)PANI was synthesized by oxidative polymerization and the influence of synthesis conditions on thermoelectric properties and the microstructure of PANI were studied.(2)The PANI was treated at several temperatures(i.e.90??120??150??180?)and the thermoelectric properties of PANI were discussed.(3)The Graphene/polyaniline composites with different contents of graphene were prepared by in-situ polymerization,and the thermoelectric parameters of which were determined.(4)Composites of Ge0.94Pb0.01Bi0.05Te/PANI were prepared by in-situ polymerization and mechanical mixing methods respectively,and the thermoelectric properties of different complexes were compared.Results are shown as follows:(1)Synthesis conditions of PANI have little influences on the Seebeck coefficient and thermal conductivity,however,synthesis conditions have greater impact on ZT values,because of the conductivity of PANI varied with changes of preparation conditions.(2)Heat treatment(90?180 ?)did not improve the thermoelectric properties of PANI,and ZT values of which decreased by nearly an order of magnitude,because of the conductivity of the material reduced after treatment.(3)Graphene improved the power factor,conductivity and thermal conductivity of Graphene/PANI composites,and the ZT value of 20%mass fraction of Graphene/PANI is larger than PANI about 90%.(4)Since Ge0.94Pb0.01Bi0.05Te has better thermal performance,thermoelectric properties of Ge0.94Pb0.01Bi0.05Te/PANI composites which were prepared by in-situ polymerization and mechanical mixing has been improved,the rate increased by an order of magnitude or so.Through this work,some conclusions can be gained:the conductivity is a major limiting factor to improve the thermolelectric performance of PANI,the conductivity and thermoelectric properties of PANI can be effectively improved by some method(i.e.in-situ polymerization,complexing,etc).