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The fractal dynamics of epoxy polymers curing in the presence of carbon nanotubes

DOI 10.18127/j19997493-201901-02

Keywords:

L.B. Atlukhanova – Ph.D.(Pedagogic), Associate Professor, Department of Biophysics, Informatics and Medical Devices, Dagestan State Medical University (Makhachkala)
E-mail: bremovna77@mail.ru
G.V. Kozlov – Senior Research Scientist, Kh.M. Berbekov Kabardino-Balkarian State University (Nalchik)
E-mail: i_dolbin@mail.ru


The curing process of epoxy polymers in the presence and absence of carbon nanotubes was studied within the frameworks of dynamics of composite systems. The introduction of carbon nanotubes changes structure of epoxy polymer microgels, that is identical to action of variation of curing temperature. The indicated changes are defined strong variation of kinetics of epoxy polymers curing.
The curing process of epoxy polymers in the presence and absence of carbon nanotubes is considered within the framework of general physical conceptions, namely, as self-organization of composite system, developing in time, that leads to temporal structures formation. Such approach allows to use for the indicated process description a methods of dynamics of composite systems. The Harts exponent, which is multifunctional characteristic, was choosed as main characteristic of process. Such treatment allows to select two dynamic fields of curing process: if the Harts exponent varies within the limits of 0−0.5 then curing is described by dynamics of random structureless process on its initial stages and the Harts exponent 0.5 characterizes Gaussian structureless process. If the indicated exponent exceeds 0.5 then reactive medium becomes dynamic system with determined chaos, having fractal temporal structure. The Harts exponent is interconnected synonymously with dimension of fractal (fractal0like) molecule of epoxy olygomer in curing process. The methodics of determination of the indicated dimension on the basis of kinetic characteristics of curing process. Within the framework of this dynamic model curing kinetics as a function of temperature was studied and it has been shown that at 473 K the transition from dynamics of random structureless process to dynamics of system with determinated chaos happens. The introduction of carbon nanotubes in reactive medium gives both quantitative and qualitative effect. At temperatures lower then 473 K introduction of nanotubes causes the described above transition and at higher temperatures the Harts exponent growth is observed without change of system dynamics type. The change of curing dynamics type leads to qualitative change of diffusive processes for the considered reaction. In the case of dynamics of random structureless process the slow anomalous (strange) diffusion of reagents is realized and at dynamics of system with determinated chaos-fast anomalous diffusion. At the same time both connectivity degree of reactive medium and dimension of reagents walk trajectories are changed. It is important from the practical point of view that the described above transition defines sharp acceleration of epoxy polymers curing process.

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