0000000000013532
AUTHOR
Silvia Bistarelli
showing 5 related works from this author
Electrical transport in carbon black-epoxy resin composites at different temperatures
2013
Citation: J. Appl. Phys. 114, 033707 (2013); doi: 10.1063/1.4815870 (Received 3 May 2013; accepted 27 June 2013; published online 17 July 2013) Results of broadband electric/dielectric properties of different surface area—carbon black/epoxy resin composites above the percolation threshold are reported in a wide temperature range (25–500 K). At higher temperatures (above 400 K), the electrical conductivity of composites is governed by electrical transport in polymer matrix and current carriers tunneling from carbon black clusters to polymer matrix. The activation energy of such processes decreases when the carrier concentration increases, i.e., with the increase of carbon black concentration…
Electromagnetic shielding efficiency in Ka-band: carbon foam versus epoxy/carbon nanotube composites
2012
The wide application of microwaves stimulates searching for new materials with high electrical conductivity and electromagnetic (EM) interference shielding effectiveness (SE). We conducted a comparative study of EM SE in K a -band demonstrated by ultra-light micro-structural porous carbon solids (carbon foams) of different bulk densities, 0.042 to 0.150 g/cm 3 , and conventional flexible epoxy resin filled with carbon nanotubes (CNTs) in small concentrations, 1.5 wt.%. Microwave probing of carbon foams showed that the transmission through a 2 mm-thick layer strongly decreases with decreasing the pore size up to the level of 0.6%, due to a rise of reflectance ability. At the same time, 1 mm…
Microwave response properties of epoxy resin composites filled with graphitic fillers
2014
Composite materials based on epoxy resin filled with various kinds of graphite particles: exfoliated graphite (EG), natural graphite, and coarse, medium and fine artificial graphites have been prepared. The dielectric permittivity strongly increases with graphite particle size. This effect is related to the distance of the investigated filler concentrations to the composites' percolation threshold. Microwave experiments show that exfoliated graphite is, out of investigated graphite particles, the only one being a really effective additive for producing electromagnetic (EM) interference (EMI) shielding: 2 wt.% epoxy/EG is absolutely opaque to electromagnetic radiation at 30 GHz.
Novel non-destructive evaluation technique for the detection of poor dispersion of carbon nanotubes in nanocomposites
2019
Abstract A wide use of advanced carbon nanotube polymer composites can be boosted by new non-destructive evaluation (NDE) techniques that can test the quality of the products to ensure that their specifications are met. It is well known in literature that the parameter that far more than others can affect the enhancing capabilities of the carbon nanotubes is their dispersion. Here we have presented a novel NDE technique based on infrared thermography able to evaluate the dispersion of the added nanoparticles in polymer nanocomposites. The NDE technique was used to compare pairs of samples whose difference is represented only by the level of dispersion. It was found a significant difference …
Dielectric properties of graphite-based epoxy composites
2014
International audience; Composite materials based on epoxy resin filled with various kinds of graphite particles: exfoliated graphite, natural graphite, and coarse, medium and fine artificial graphites have been prepared. Results of broadband dielectric investigations of such materials in wide temperature (25-450 K) and frequency (20 Hz-3 THz) ranges are presented. The dielectric permittivity strongly increases with graphite particle size. The graphite particle size and shape also have a strong impact on freezing temperature, conductivity activation energy and composite electromagnetic absorption properties at room temperature. The lowest percolation threshold is observed for exfoliated gra…