Preparation And Thermoelectric Properties Of Nanocarbon/Polyaniline Composites

Polyaniline （PANI） is considered as one of the most promising polymerthermoelectric material due to its low thermal conductivity, easy synthesis,environmental stability and so on. However, the thermoelectric conversion efficiency ofpolyaniline is still too low. In this thesis,carbon nanotubes were modified byacidificating, graphene dispersing and loading silver. The effects of different carbonfillers on the structure, morphology and thermoelectric properties of polyanilinecomposites were studied. The tendency of the amount of carboxyl carbon nanotube andthe mass ratio of nanocarbon and silver nitrate on the thermoelectric performance ofpolyaniline composite materials were also studied.Graphene was used as the surfactant to improve carbon nanotube’s dispersivity inpolyaniline matrix. When the mass ratio of graphite oxide and carbon nanotubes is1:1,the well dispersed nanocarbon can be obtained. Silver nanoparticles load on the surfaceof nanocarbon evenly with an average diameter of20nm in the process of Ag loadednanocarbon when the ratio of nanocarbon and silver nitrate is1:0.85, the reactiontemperature is60℃and the reaction time is4h.In the temperature range of50-180℃， the thermoelectric performance ofpolyaniline composites filled with different nanocarbon were studied. It indicates thatAg loaded nanocarbon can significantly increase the power factor of polyanilinecomposites. The power factor of Ag loaded nanocarbon/polyanilne can reach9.9210-8W.m^-1.K^-2at50℃, which is about13.5times of PANI. The power factor ofnanotube/polyanilne can reach7.0510-7W.m^-1.K^-2at180℃,which is higher than thatof PANI by about31%.The tendency of the amount of carboxyl carbon nanotubes on the thermoelectricproperties of polyaniline composite was investigated. It indicates that when the amountof carbon nanotube is2.5mass%, the electrical conductivity is20.27s.cm^-1at100℃,higher than that of pure PANI by about17%. The Seebeck coefficient can reach28.8μV·K^-1around150℃, higher than that of PANI by71.4%. The power factor is1.19×10-6W.m^-1.K^-2, which is2.38times of PANI. Though the addition of CNT slightlyincreased the thermal conductivity of composites, the ZT of carbon nanotube/polyanilnecan reach1.7610-3at150℃, which is2.24times of PANI.Adding Ag loaded nanocarbon could significantly improve the Seebeck coefficientof polyaniline composites when the effect of mass ratio of nanocarbon with silvernitrate on the thermoelectric properties of Ag loaded nanocarbon/polyaniline wasstudied. The thermal conductivity of the composites is lower than that of purepolyaniline because of the strong effects on the phonon scattering of silver nanoparticles and nano carbon phase. When the mass ratio of nanocarbon with silver nitrate is1:1.7,the thermal conductivity of the composite material is0.26W.m^-1.K^-1around45℃, whichis lower than that of PANI by15.2%. When the mass ratio of nano carbon with silvernitrate is1:0.42, the power factor of Ag loaded nano carbon/polyaniline can reach8.1910-7W.m^-1.K^-2at150℃, which is1.67times of the pure PANI. The ZT of thecomposite can reach1.3710-3,which is73.7%higher than that of PANI.