Influence of crystallinity and chain interactions on the electrical properties of polyamides/carbon nanotubes nanocomposites

摘要

This work evaluates the effects of the crystallinity degree and pi-pi interactions between nanoparticles and a polymeric matrix on the electrical properties of polyamides and carbon nanotubes (CNT) nanocomposites. Two polymeric matrices were chosen; polyamide (PA) 6.6, a semi-crystalline polymer, and PA 6I-6T (here called aPA), a semi-aromatic and amorphous polyamide. The PA 6.6 crystallinity degree did not significantly change. Both lamellar thicknesses, amorphous (L-a) and crystalline (L-c), were estimated through Small-angle X-ray scattering. L-a increased significantly when CNTs were added. Both nanocomposites presented almost the same percolation threshold. In aPA nanocomposites, the pi-pi interaction between aromatic groups of CNTs and aPA is not only responsible for a homogeneous CNT dispersion, but also creates a direct path, parallel to the electrodes, for electron conduction after the percolation limit. In the PA 6.6 nanocomposites, the CNTs preferably disperse in the amorphous regions, forming a conductive network.