Authors: Ch. Pandis, E. Logakis, M. Chorianopoulos, A. Spanoudaki, A. Kyritsis, V. Peoglos, P. Pissis, M. Micusík, I. Krupa, M. Omastová, J. Pionteck and P. Pötschke
Affilation: National Technical University of Athens (NTUA), Greece
Pages: 166 - 169
Keywords: nanocomposites, polypropylene, carbon nanotubes, thermal transitions, electrical properties
The influence of multi-walled carbon nanotube (MWCNT) content on electrical/dielectric and thermal properties of CNTs-reinforced polypropylene (PP) nanocomposites is studied. We focus on the investigation of electrical and dielectric properties in relation to percolation: ac and dc conductivity, σac and σdc, respectively, above the percolation threshold (pc) and dielectric permittivity, ε′, below pc. To that aim we employ broadband dielectric relaxation spectroscopy (DRS) and dc conductivity measurements. In addition, we examine the effect of the addition of MWCNTs in the thermal transitions (glass transition, crystallization, melting) of the nanocomposites by differential scanning calorimetry (DSC) measurements. Masterbatch granules containing polypropylene and 20 wt. % of MWCNT were used as components for the preparation of the thermoplastic composites with lower CNT contents and of blends with maleic anhydride (MA) modified polypropylene. The final concentration of the samples in CNTs was varied from 0.2 to 8 wt %. A shift of the crystallization peak to higher temperatures is observed by increasing the amount of CNTs in the PP matrices (crystallization rate increases because of CNTs’ action as crystallization nuclei.From DRS measurements of MA modified PP/CNTs series we can see the transition from the insulating to the conductive phase (independence of frequency) at 3.3 – 4 wt% CNTs content.