The effect of filler aspect ratio on the electromagnetic properties of epoxy-amine resin reinforced with carbon nanofibers is here investigated. A heat treatment at 2500°C of carbon nanofibers seems to increase their aspect ratio with respect to as-received ones most likely due to a lowering of structural defects and the improvement of the graphene layers within the dixie cup conformation. These morphological differences revealed by Raman's spectroscopy and scanning electron microscopy analyses may be responsible for the different electrical properties of the resulting composites. The DC characterization of the nanofilled material highlights an higher electrical conductivity and a lower electrical percolation threshold for the heat-treated carbon nanofibers based composites. In fact, the electrical conductivity is about 0.107S/m and 1.36×10-3S/m for the nanocomposites reinforced with heat-treated and as received fibers, respectively, at 1wt.% of nanofiller loading, while the electrical percolation threshold falls in the range [0.05-0.32]wt.% for the first nanocomposites and above 0.64wt.% for the latter. Moreover, also a different frequency response is observed since the critical frequency, which is indicative of the transition from a resistive to a capacitive-type behaviour, shifts forward of about one decade at the same filler loading. The experimental results are supported by theoretical and simulation studies focused on the role of the filler aspect ratio on the electrical properties of the nanocomposites.
The effect of filler aspect ratio on the electromagnetic properties of carbon-nanofibers reinforced composites
DE VIVO, BIAGIO;LAMBERTI, PATRIZIA;SPINELLI, GIOVANNI;TUCCI, Vincenzo;GUADAGNO, Liberata;RAIMONDO, MARIALUIGIA
2015
Abstract
The effect of filler aspect ratio on the electromagnetic properties of epoxy-amine resin reinforced with carbon nanofibers is here investigated. A heat treatment at 2500°C of carbon nanofibers seems to increase their aspect ratio with respect to as-received ones most likely due to a lowering of structural defects and the improvement of the graphene layers within the dixie cup conformation. These morphological differences revealed by Raman's spectroscopy and scanning electron microscopy analyses may be responsible for the different electrical properties of the resulting composites. The DC characterization of the nanofilled material highlights an higher electrical conductivity and a lower electrical percolation threshold for the heat-treated carbon nanofibers based composites. In fact, the electrical conductivity is about 0.107S/m and 1.36×10-3S/m for the nanocomposites reinforced with heat-treated and as received fibers, respectively, at 1wt.% of nanofiller loading, while the electrical percolation threshold falls in the range [0.05-0.32]wt.% for the first nanocomposites and above 0.64wt.% for the latter. Moreover, also a different frequency response is observed since the critical frequency, which is indicative of the transition from a resistive to a capacitive-type behaviour, shifts forward of about one decade at the same filler loading. The experimental results are supported by theoretical and simulation studies focused on the role of the filler aspect ratio on the electrical properties of the nanocomposites.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
