Registration Number
0210U005107,
0107U007694
, R & D reports
Title
Structure, stability and percolation properties of nanocomposites, which include carbon materials and layered-silicates
popup.stage_title
Head
Lebovka Nickolai Ivanovich,
Registration Date
07-06-2010
Organization
F.D. Ovcharenko Institute of biocolloidal Chemistry NAS of Ukraine
popup.description2
In this report is devoted to the results of the theoretical and experimental research of the percolation behavior of the nanocomposites filled with the anisotropic particles. In theoretical research, we used such common models, as model of random sequential adhesion (RSA) and general model of slow coagulation with kernel where the Fuchs' dynamic stability factor was taken into account. It was shown that a mechanism of orientation restructuring of particles on the substrate reinforces the percolation for the RSA model. Due to this mechanism a charge transport through an interparticle contact is possible. At the same time, the RSA model without the mechanism of orientation restructuring of particles on the substrate shows that the percolation is appears only in case of tunnel mechanism of the charge transport. For the general model of slow coagulation with kernel, which includes the Fuchs' dynamic stability factor, the significant decreasing of the aggregation velocity in compare to prediction of the Smoluchowski-Fuchs' classical model was shown. The factor of electrostatic stabilization in this model leads to reducing of the width of distribution function and the mean size of secondary particles. Based on this prediction the effective method of the regulation of the size and the polydispersity of nanoparticles of polyelectrolyte complexes, which were produced by the mixing of polyanyons and polycations at the different nonstoichiometric ratio, was suggested. The composite systems, which demonstrate the percolation behavior of electric conductivity with ultralow percolation threshold (0.02-0.1% mass of nanotubes) were obtained as the result of experimental study of behavior of disperse media (polymers, liquid paraffin, nematic liquid crystals, bensophenon) filled with multiwall carbon nanotubes (NT). It was shown that this behavior is the result of the segregation of NT and their high aspect ratio. In this composite systems an effect of positive temperature coefficient of electrical conductivity, a hysteresis in cycles of heating and cooling and an influence of thermal history on the structure and behavior of composites were observed. Using the jumping model for the electrical transport in nanocomposites give us an explanation for the nonohmic behavior of electrical conductivity and frequency dependencies at the different filling of NT. The results of investigations can be used both at the development of methods of the synthesis of nanoparticles and composites and the determination of the mechanism of percolation behavior and the electrical conductivity of nanocoposites in disperse media with different nature (polymers, liquid crystals etc).
Product Description
popup.authors
Бойко Ю.П.
Вигорницький М. В
Гончарук А. І.
Логінов М. О.
Солов'йова О. О.
Старченко В.Ю.
popup.nrat_date
2020-04-02
