Influence of the modification, induced by zirconia nanoparticles, on the structure and properties of polycarbonate

Melt compounding was used to prepare polycarbonate (PC)-zirconia nanocomposites with different amounts of zirconia. The effect of the zirconia loading, in the range of 1-5 wt.%, on the structure, mechanical properties and thermal degradation kinetics was investigated. The zirconia nanoparticle aggregates were well dispersed in the PC matrix and induced the appearance of a local lamellar order in the polycarbonate as inferred by SAXS findings. This order could be a consequence of the intermolecular interactions between zirconia and the polymer, in particular with the quaternary carbon bonded to the methyl groups and the methyl carbon as inferred from the NMR results. The presence of zirconia caused a decrease in the storage and loss moduli below the glass transition temperature. However, the highest amount of zirconia increased the modulus. The presence of zirconia in PC slightly increased the thermal stability, except for the highest zirconia content which showed a decrease. The activation energies of thermal degradation for the nanocomposites were significantly lower than that for pure PC at all degrees of conversion.