Electrical and thermal conductivity of composites which contain carbon-based fillers in an epoxy matrix were investigated. The fillers were dispersed in the liquid matrix by using three roll mill equipment. The filler/matrix mixture was cast in a mold and then cured, thus obtaining composite specimens. Multiwall carbon nanotubes, graphene-like nanoplatelets, and graphite were used as fillers and their effect on conductivity was investigated. Electrical and thermal conductivity were measured at different filler loads. It was found that the formation of percolation paths greatly enhanced electrical conductivity, although they were not so effective in improving thermal conductivity. The behavior of composites containing each single filler was compared with that of hybrid composites containing combinations of two different fillers. Results show that fillers with different aspect ratios displayed a synergetic effect resulting in a noticeable improvement of electrical conductivity. However, only a small effect on thermal conductivity was observed.

Polypropylene (PP), acrylonitrile butadiene styrene (ABS), and thermoplastic polyurethane (TPU) nanocomposites filled with 5 wt % of two different kinds of commercially available graphene nanoplatelets (GNPs) were prepared. Composites materials were characterized in terms of thermal properties (thermal conductivity and thermal stability) in order to study the effect of different fillers within different thermoplastic matrices. The exfoliation process and the mechanical properties were also investigated. We chose three different thermoplastic polymers (polyolefin, copolymer and elastomer) to cover a wide range of thermoplastic materials and identify a guideline in the use of GNPs for nanocomposite materials. No drastic differences were observed in terms of mechanical properties when the same matrices were filled with different GNPs. Concerning thermal conductivity, it was observed that the GNPs plane dimensions play a crucial role in the increase of conductive properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44814.

The effect of carbon nanotubes, graphene-like platelets, and another carbonaceous fillers of natural origin on the electrical conductivity of polymeric materials was studied. With the aim of keeping the filler content and the material cost as low as possible, the effect of laser surface treatments on the conductivity of polymer composites with filler load below the percolation threshold was also investigated. These treatments allowed processing in situ conductive tracks on the surface of insulating polymer-based materials. The importance of the kinds of fillers and matrices, and of the laser process parameters was studied. Carbon nanotubes were also used to obtain piezoresistive composites. The electrical response of these materials to a mechanical load was investigated in view of their exploitation for the production of pressure sensors and switches based on the piezoresistive effect. It was found that the piezoresistive behavior of composites with very low filler concentration can be improved with proper laser treatments.

Metal-free conductive tracks were obtained on polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS)-multiwall carbon nanotube (MWCNT) nanocomposites by laser printing technology. Laser printing is a novel technique able to promote polymer pyrolysis leading to the formation of conductive tracks embedded on the surface of polymer-based nanocomposites. The resulting material is characterized by the presence of different not interactive conductive pathways. The aim of this article is to analyze the effect of the laser parameters setup on the electrical resistivity of laser printed tracks. To have a complete comprehension of the process, a design of experiment (DOE) approach was used. By analyzing the experimental outcomes with a statistical approach, it was possible to focus the attention on the main laser parameters that govern the process, thus obtaining multifunctional and multidirectional conductive materials with surface electrical resistance per length unit (inside the tracks) lower than 1 kX/cm at 0.5 wt% of MWCNT loading content. POLYM. ENG. SCI., 00:000-000, 2017.

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