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DIELECTRIC PROPERTIES OF POLYURETHANE NANOCOMPOSITES MODIFIED BY FULLERENE С60 AND NANODIAMONDS

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The paper describes preparation of polyurethane composites infused with nano- and macro-sized carbonaceous fillerswith a different surface nature (with a hydrophobic surface-fullerene C60, fullerene soot, with a hydrophilic surface nano-diamonds, nano-diamond charge), with loading varying from 0.1 to 0.5 wt. % by in situ polymerization. The obtained nano-composites were measured by the method of dielectric spectroscopy to determine the nature of the influence of the surface origin and particle size on the structure and properties of the finished material. It was found that loading of fillers leads to the decrease in the process of α-relaxation activation energycompared to neat polyurethane (PU). It was revealed that the non-specific π-π interaction for nanosized fillers dominates over specific H-bonding, which can be related to the oxygen groups on the shells of nano-diamonds. The dielectric spectroscopy demonstrated that the glass transition temperature values of the nano-composites increase in comparison with neat PU, manifesting the so-called "antiplasticizating phenomenon", while composites with macro-sized filler exhibit a typical plasticizing effect for traditional fillers. The greatest value of the D parameter (fragility) corresponds to a sample with fullerene soot. The coincidence of activation energies of Maxwell-Wagner-Sillars polarization for different fillers means that the dimensions of the hard domains in the polymer have not changed.

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