The analysis of the temperature dependence of catalytic activity of carbon nanotubes at epoxy polymers curing within the frameworks of fractal analysis

The structural (fractal) model, describing the dependence of catalytic ability of carbon nanotubes in process of epoxy polymers curing, was proposed. Enhancement of epoxy polymers curing temperature leads to growth of constant of reaction rate for both initial epoxy polymers and systems epoxy polymer/carbon nanotubes, but for the last this effect is expressed much stronger. This means existence of catalytic effect of carbon nanotubes, which intensifies at temperature enhancement at their constant concentration. It has been found that constant of catalysis rate of second order is proportional to the difference of constants of curing reactions rate for system epoxy polymer/carbon nanotubes and initial epoxy polymer. This circumstance assumes that catalytic ability of carbon nanotubes in curing process is connected with their structure and specifically – with surface structure of this nanofiller aggregates. Reduction of this surface fractal dimension leads to increasing of catalytic ability of carbon nanotubes. The indicated ability is also a function of structure of reaction product – microgel, i.e. cross-linked macromolecular coil of epoxy polymer. Enhancement of microgel fractal dimension defines increasing of constant of catalysis rate. This means that efficiency of catalysis of epoxy polymers curing by carbon nanotubes is controlled by difference of fractal dimensions of microgels for the considered systems. The limiting temperature of curing exists, at which catalyzing action of carbon nanotubes ceases. Hence, two structural factors are defined catalytic ability of carbon nanotubes: by structure of catalyst (carbon nanotubes) surface and structure of forming in curing process microgel of epoxy polymer.