Effect of surface nature of carbonaceous nanosized fillers on properties of polyurethane based nanocomposites

Polyurethane (PU) composites containing uniformly dispersed nanosized and macrosized carbonaceous fillers (fullerene C60, fullerene soot, detonation nanodiamonds, and nanodiamonds soot) with loadings varying from 0.1 to 0.5 wt.% were prepared by in situ polymerization. The kinetics of PU synthesis catalyzed by dibutyltin dilaurate was studied as a function of amount of nanosized filler. It was found that the reaction is zero-order. The kinetics of the hard domain growth of the PU matrix was studied and described successfully using the two-parameter Avrami model for isothermal crystallization. It was found that the growth of polymers induces athermal primary nucleation for hard domain growth, and that nanosized fillers do not change the nucleation mechanism. Our results show that the mechanical strength of PU composites increases in the presence of all types of nanoparticles under study. This can be related to the antiplasticization effect of the nanoparticles on the polymer matrix. The dielectric spectroscopy demonstrated that T-g values of the composites increase in comparison with neat PU. However, the effects of hydrophilic/hydrophobic properties of nanoparticles on the secondary relaxations are not obvious Microphase separation in these nanocomposites was studied using FTIR spectroscopy, but no effect of surface properties of the nanoadditives on this phenomenon has been observed.