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Papers by Elilton Edwards

Matéria (Rio de Janeiro)

Composite with nanometric particles have been used as a structural reinforcement to improve the m... more Composite with nanometric particles have been used as a structural reinforcement to improve the mechanical properties in polymeric materials. The use of graphene has shown excellent results such as Young's modulus of 1 TPa, tensile strength of about 130 GPa, thermal conductivity of 5000 W/mK, electrical conductivity of up to 6000 S/cm, in addition to presenting great carrier mobility of loads of 2x105 cm2.V-1.s-1. Thus, the mechanical properties in the epoxy resin based on diglycidyl ether of bisphenol A were evaluated with the addition of increasing percentages of graphene oxide (GO) in order to evaluate the mechanical properties in this material. The synthesis of GO was made from natural graphite by the Hummers method. The nanostructured composites were manufactured with a mixture of 0.1%, 0.2%, 0.5% and 1% by weight of GO. The characterizations of the materials were made by FTIR-ATR, DRX, RAMAN, MEV and TGA. The mechanical properties were evaluated by increasing the impact en...

Journal of Polymer Research, 2022

In this work, were evaluated the influence of UV radiation on the chemical structure of the compo... more In this work, were evaluated the influence of UV radiation on the chemical structure of the composite fabricated with epoxy resin N,N,N`,N`- tetraglycidyl-4,4` diaminodiphenylmethane (TGDDM) and the hardener 4.4` diaminodiphenyl sulfone (DDS) for space application. Carbon nanotubes were functionalized with acyl chloride (SOCl2) and by varying the nanostructured composites were processed by using epoxy resin with MWCNT-f in varying percentages. The penetration depth of UV radiation in composites exposed in a UV camera for 4320 h was evaluated by Fourier transform infrared spectroscopy (FTIR) coupled with attenuated total reflectance (ATR) coupled. Structural characterizations were performed with Scanning Electron Microscopes (SEM). The analysis of protection against the degradation of polymeric chains was evaluated with the addition of increasing amounts of functionalized carbon nanotubes (MWCNT-f). It was observed that with the addition of 1% MWCNT-f there was a better formation of barriers against the penetration of UV avoiding the degradation of the material.

Canadian Metallurgical Quarterly, 2017

ABSTRACT A Nb–10%W (wt-%) alloy ingot was produced via aluminothermic reduction of a Nb2O5+ WO3 m... more ABSTRACT A Nb–10%W (wt-%) alloy ingot was produced via aluminothermic reduction of a Nb2O5+ WO3 mixture followed by electron beam melting. The O and N contents of the ingot after triple EBM steps were 63 wt-ppm and 32 wt-ppm, respectively. This alloy presents potential for application as artificial pinning centre (APC) in Nb–Ti superconducting wires due to its high residual resistivity compared to pure Nb, which is a necessary characteristic to increase critical current density at high magnetic fields. The cold plastic deformation behaviour of this material was studied and compared to that of Nb–Ti and pure Nb. The hardening behaviour of the Nb–10W alloy was unusual as compared to others Nb alloys presumably due to unexpected inhomogeneity of the alloy even after cold plastic deformation and annealing at 1300°C for 4 h.

Colecao Prope Digital, 2012

Journal of Nanoscience and Nanotechnology, 2011

Composite of multi-walled carbon nanotubes (MWCNT) and epoxy resin DGEBA were obtained with DDM h... more Composite of multi-walled carbon nanotubes (MWCNT) and epoxy resin DGEBA were obtained with DDM hardener. The MWCNT were synthesized with length of millimeters by camphor/ferrocene pyrolysis. Different cure temperatures of DGEBA/DDM with addition of up to 1% MWCNT were studied to evaluate eventual changes in cure kinetics by differential scanning calorimetry (DSC). No change was detected in glass transition temperature with insertion of MWCNT although the cure enthalpy has been reduced.

Journal of Materials Research, 2012

Systematic studies have been carried out for investigating the mechanical properties of carbon na... more Systematic studies have been carried out for investigating the mechanical properties of carbon nanotube (CNT)-reinforced phenolic resin. In this work, phenolic resin/CNT nanocomposite were processed using two different techniques: (i) three-roll calender device (TRC) and (ii) aqueous solution processes. In both techniques, up to 2 wt% CNT was used. In this study, it was observed that the values of tensile strength, Young's modulus, shear stress, impact resistance and also that of the tribological properties increased directly proportional to carbon nanotube volume content. Halpin-Tsai, Voigt-Reuss and Cox equations were adopted to fit the experimental data of the tensile strength and Young's modulus of the multiwalled carbon nanotube/phenolic resin composite. Morphological analysis was done utilizing scanning electron microscopy (SEM) and good dispersion of nanotubes within the phenolic resin matrix was revealed. Also according to the results presented in this work, SEM showed that TRC processing gave better dispersion than aqueous solution mixing. The observation that the values for mechanical properties increased more for TRC than aqueous mixed samples is consistent with this.

Composites Part B: Engineering, 2013

ABSTRACT In this work, the chemical interaction between carbon nanotubes (MWCNT) functionalized w... more ABSTRACT In this work, the chemical interaction between carbon nanotubes (MWCNT) functionalized with acyl chloride (SOCl2) and polymer chain tetrafuncional N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) and hardener 4,4′diaminodiphenyl sulfone (DDS) has been monitored by Fourier transform infrared spectroscopy (FTIR) with a attenuated total reflectance (ATR) coupled. MWCNT were obtained from the pyrolysis of a mixture of camphor and ferrocene into a oven. The functionalization process was done by oxidative treatment in order to incorporate carboxylic group over the walls of MWCNT, before to be used SOCl2. The functionalized carbon nanotubes were evaluated by X-ray photoelectron spectroscopy (XPS), Raman and transmission electron microscopy (TEM). Nanostructured composites were processed by using epoxy resin with MWCNT in varying percentages. In this work it was observed that different percentages of functionalized nanotubes modify the interaction between the composite matrix and curing agent, where can be observed that in specimens with content less than 1 wt% MWCNT the chemical bond occurs preferentially from the opening of the SO double bond of the hardener and when is used MWCNT content higher than 1 wt% there is little chemical interaction with the SO bond of the hardener and most MWCNT binds to amine.

Superconductor Science and Technology, 2006

The present work presents the steps for the manufacture of an Nb-Ti artificial pinning centre (AP... more The present work presents the steps for the manufacture of an Nb-Ti artificial pinning centre (APC) multifilament wire for AC applications. The wire production starts from a Ti bar inserted in a Nb tube. The superconductor Nb-Ti alloy was obtained using heat treatments during the wire production steps through the growth of the diffusion layer between the pure Nb and Ti regions. The final wire is composed of many filaments dispersed in a Cu-Ni matrix. The transport critical current density was measured in samples for different conditions of heat treatment, followed by wire diameter reduction. Magnetization hysteresis loops were measured to extract the hysteretic losses in wires with filament diameters of 76 and 92 µm and compared to the results in commercial wires with comparable filament diameters. We obtained an Nb-Ti APC wire with hysteretic losses of the same order of magnitude as the commercial wires. However, critical current densities Jc are higher for fields lower than 2 T, where AC applications are most important. The Jc results confirmed a previous result that the decrease of normal region sizes is a less important pinning source in this material than the pinning from variations in the composition of the diffusion layer.

Revista Ibero-Americana de Humanidades, Ciências e Educação, 2021

Grafeno é uma monocamada com estrutura hexagonal de átomos de carbono e que tem se tornado um mat... more Grafeno é uma monocamada com estrutura hexagonal de átomos de carbono e que tem se tornado um material de grande interesse para os pesquisadores da nanotecnologia e nanociência. Neste artigo foi analisada a viabilidade da aplicação do grafeno tanto oxidado como reduzido para uso como eletrodo em capacitores eletroquímicos. A síntese do óxido de grafeno foi obtida através do método modificado de Hummels-Hofmann e posteriormente a redução química e térmica deste material. As caracterizações dos materiais foram realizadas pelas técnicas de Difração de raios-x (DRX), Espectroscopia de Infravermelho e Espectroscopia Raman. Análises por DRX apresentou uma esfoliação suave para o óxido de grafeno tendo como precursora a grafite. O resultado da espectroscopia de infravermelho apresentou grupos oxigenados que foram inseridos no processo da oxidação, corroborado pela técnica de espectroscopia Raman. O grafeno sintetizado foi analisado por espectroscopia Raman e apresentou grafeno de multifol...

Superconductor Science and Technology, 2003

Quantitative data on the diffusion between Nb and Ti are important for the processing of Nb-Ti su... more Quantitative data on the diffusion between Nb and Ti are important for the processing of Nb-Ti superconductor wires through the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#x27;artificial pinning centre-diffusion process&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#x27;. In the literature, most of the Nb-Ti diffusion studies are focused on the 1173-1973 K temperature range which is inappropriate for this application. The objective of this study was to evaluate the diffusion between Nb and

Journal of the Brazilian Chemical Society, 2011

Applied Surface Science, 2011

A detailed analysis by X-ray photoelectron spectroscopy was carried out on multi-walled carbon na... more A detailed analysis by X-ray photoelectron spectroscopy was carried out on multi-walled carbon nanotube (MWCNT) surfaces after non-oxidative and oxidative purification treatments in liquid-phase. The MWCNT were produced by pyrolysis of camphor and ferrocene, that provides a high yield but with high iron contamination (∼15%wt). The elimination and/or oxidation of iron nanoparticles were monitored by Fe2p and O1s core level.

Polímeros

In this study, the chemical interaction between functionalized carbon nanotuboes with carboxyl gr... more In this study, the chemical interaction between functionalized carbon nanotuboes with carboxyl groups (CNT-f) and the subsequent addition of furfuryl alcohol (FA) and mixture with poly(furfuryl alcohol) (PFA) resin was evaluated. The FA with CNT-f was mixed in PFA resin to facilitate the chemical interaction of CNTs. The morphological and chemical interaction were studied by Transmission Electron Microcopies (MET), FTIR analyses, Raman Spectroscopy, viscosimetry and X-ray photoelectron spectroscopy (XPS). It was observed that a chemical interaction occurs through the opening of the hydroxyl polymer chain with a subsequent output of one water molecule. This interaction was evident from the FTIR and XPS data of the PFA composites. In this way, the mixture of functionalized carbon nanotubes with carboxyl groups in the FA, before adding this reinforcement into the PFA resin, can be considered a good procedure in order to obtain an appropriate chemical interaction between the CNT and PFA resin.