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The piezoelectric properties of Poly(vinylidene fluoride) (PVDF) mainly depend on its most polar y9-phase. In this work, we investigated through Piezoresponse Force Microscopy (PFM) the piezoelectric properties of PVDF composite films when we induce the formation of y9-phase crystals adding graphene nanoplatelets (GNPs) without any chemical modification or poling. At first, we fabricated GNP-filled...
Poly(vinylidene fluoride) (PVDF) is a biocompatible polymer commonly used for biomedical applications, food packaging and hygiene products. Within these contexts, the polymer surface is typically exposed to microorganisms and bacteria, with consequent biofilm formation. In this paper, self-standing flexible composite poly(vinylidene fluoride)(PVDF) films with antimicrobial properties were prepared...
A novel lightweight wideband radar absorbing material (RAM) for radio-frequency is developed using a rohacell (RC) panel coated with a film of carbon nanostructures. The coating is produced through the dispersion of either commercial graphene nanoplatelets (GNPs) or carbon nanofibers (CNFs) in 1-propanol and the deposition of the so-obtained colloidal suspension onto the RC surface with a bristle...
A graphene-based porous paper made of multilayer graphene (MLG) microsheets is developed for application as a flexible electrically conducting shielding material at radio frequency. The production process is based on the thermal expansion of a graphite intercalated compound, the successive liquid-phase exfoliation of the resulting expanded graphite in a proper solvent, and finally the vacuum filtration...
In recent years, several studies have demonstrated the strong cytotoxicity toward bacteria of graphene-based materials, suggesting their use as antimicrobial agents. The objective of this study was to evaluate the antibacterial activity against Streptococcus mutans, the principal microbiological agent in the etiology of dental caries, of two types of graphene nanoplatelets (GNPs), characterized by...
Epoxy-based vinyl ester nanocomposites filled with graphite nanoplatelets (GNPs) are developed for applications as radar absorbing materials at radio frequency. The main scope of this study is the scale-up of the fabrication process of nanocomposites with improved mechanical and electromagnetic properties, for large-scale aeronautical application. To this purpose the use of commercially available...
In this work we analyze the feasibility of a broadband radar absorbing material made with an aeronautical grade honeycomb panel, coated with a thin conducting film of multilayer graphene nanoplatelets (MLGs). The film is deposited over the surface of a phenolic-aramid sheet and characterized in terms of sheet resistance and thickness. The morphology of the multilayer graphene flakes is analyzed by...
Multilayer graphene (MLG)/polydimethylsiloxane (PDMS) composite has been prepared by infiltrating free-standing MLG paper, obtained through the vacuum filtration of MLG-suspension using a nanoporous filter, with PDMS prepolymer. Electrical properties of both free-standing MLG paper and MLG/PDMS composite paper were investigated by four-point probe measurements. The obtained results show that the annealed...
Electroactive self-standing flexible composite poly(vinylidene fluoride) ( PVDF) films were prepared by simple solution casting method. In this study we investigated the effect of two different nanofillers, namely GNPs and ZnO NRs and the use of five different hexahydrate salts (HS) on the nucleation of the electroactive phase in the solution derived PVDF films. FT-IR analysis revealed that both HS...
In this work we investigate the shielding properties of graphene-based films, produced by spray casting deposition, which is a cost-effective technique that can be directly scaled to industrial applications. The deposition process is optimized in order to produce uniform films made of well dispersed graphene nanoplatelets (GNP), having thicknesses in the range 3–8 microns. The sheet resistance and...
Thin and flexible freestanding graphene nanoplatelets (GNPs)-based paper-like materials are fabricated and experimentally characterized to assess their employment as radiofrequency electromagnetic interference shields. Samples are obtained by vacuum filtration of ultrasonicated suspensions. Different suspensions are prepared by mixing either acetone/DMF or acetone/NMP and worm-like exfoliated graphite...
In this work we investigate the piezoresistive effect in multilayer graphene (MLG) based films produced by two different cost-effective techniques, spray coating and drop casting. Both techniques enable the direct deposition of the sensor over the structure to be monitored. The piezoresistive behavior of the MLG-based sensors has been investigated experimentally by measuring the variation of the electrical...
A graphene-based composite, consisting of a thermosetting polymeric matrix filled with multilayer graphene microsheets (MLGs), is developed for application in thin radar absorbing materials. An innovative simulation model is proposed for the calculation of the effective permittivity and electrical conductivity of the composite, and used for the electromagnetic design of thin radar absorbing screens...
Graphene films are grown by chemical vapour deposition on copper layer and then transferred onto a silicon substrate, coated with silicon dioxide. The topological characterization of the produced film is performed by atomic force microscopy, and the sheet resistance is measured by applying the four-probe test method. The equivalent single conductor model is then used in order to analyze the signal...
Graphene and its derivatives are nowadays gaining an ever increasing attention for diverse applications, such as supercapacitors, flexible screens and nanocomposites. One of the main challenges still limiting the wide spreading use of graphene-based nanomaterials in electrical and electromagnetic applications consists in the capability of controlling their morphological properties and electrical conductivity...
The expression profile of flavour‐related genes during ripening was investigated in two peach genotypes, Bolero and OroA, which have been selected for their contrasting aroma/ripening behaviour. A new peach microarray containing 4776 oligonucleotide probes corresponding to a set of ESTs specifically enriched in secondary metabolism (μPEACH2.0) was designed to investigate transcriptome changes during...
Novel graphene-based nanocomposites, consisting of a polymeric-based system filled with graphenenanoplatelets (GNP), are developed for application as low-cost lightweight electromagnetic shielding materials. High concentration and good dispersion of the GNPs inside a thermosetting polymeric matrix is achieved in order to enhance the shielding properties of the nanocomposite through the control of...
The transient shielding performances of small transparent cubic boxes illuminated by an impulsive plane wave, exciting the frequency range up to several gigahertz, are analyzed by applying an 3D full wave method. The box is made by transparent polycarbonate walls coated with a thin nanostructured transparent film, consisting of alternating thin layers of metal (Ag) and dielectric (TiO2) materials,...
Proper control of the morphological and electrical properties of graphite nanoplatelets (GNPs) by means of the optimal setting of the process parameters representsj a crucial issue in order to obtain nanocomposites with tailored properties. In this paper we investigate the effects of some key-parameters on the electrical properties of GNPs thick films, and we discuss the correlation with the morphological...
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