Dielectric relaxation of fulleroid materials filled PA6 composites and the study of its mechanical performance

The effect of fulleroid materials (fullerene C$_{60}$ and fullerene soot which is used for fullerenes production) on the mechanical properties of polymer nanocomposites based on polyamide 6 (PA6) was investigated. Composites were synthesized by direct mixing in an extruder. Dielectric spectroscopy was used to investigate the influence of nanoparticles on relaxation processes in the polymer matrix. It is found that the segmental relaxation processes becomes faster with the addition of fullerene C$_{60}$. In contrast, the secondary processes of PA6/fullerene C$_{60}$ nanocomposites were observed to slow down with the addition of fullerene C$_{60}$. This means that the local “molecular stiffness” is increased, and a phenomenological link between the secondary relaxation times and the mechanical properties explains the increase in the Young's modulus of the nanocomposites upon the addition of C$_{60}$. These observations suggest that nanoparticles can have a qualitatively different effect on the matrix polymer dynamics at different length scales, and caution must be taken in comparing the changes in the dynamics associated with different relaxation processes.