Electrical properties of melt-mixed polypropylene and as-grown carbon nanofiber composites: Analysis of their interphase <i>via</i> the AC conductivity modeling
Antonio J. Paleo, Najoia Aribou, Yassine Nioua, Z. Samir, Lisete Fernandes, J. Agostinho Moreira, M. E. Achour
Abstract
The morphology, crystallinity, and electrical conductivity (σ′ and σ″) as a function of frequency of polypropylene (PP) melt-extruded with different amounts of as-grown carbon nanofibers (CNFs) from 0 to 1.4 vol. % are examined. The PP/CNF composites present CNF aggregates randomly distributed within the PP and an insulator–conductor transition at CNF contents near 0.9 vol. %. The degree of crystallinity of PP/CNF composites with loadings of 1.4 vol. % increases ∼15% with respect to the neat PP (∼34%), with σ´ ∼ 8.6 × 10 −5 S m −1 (σ″ ∼ 8.3 × 10 −4 S m −1 ) at 2 MHz. In addition, the values of the electrical conductivity σ int ´ ∼2.9 × 10 −6 S m −1 (σ int ″∼3.7 × 10 −4 S m −1 ) at 2 MHz, as a result of the interphase (ϕ int ∼0.05 vol. %) of the 1.4 vol. % PP/CNF composites, are estimated by the use of a modified generalized effective medium model (GEM). The analysis gathered in here indicates that the interphase between the polymer and the conducting particle may have a quantifiable effect on the electrical properties of carbon-based polymer composites, and this fact should not be neglected in the production of conducting polymer composites (CPCs) with enhanced electrical properties.