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662 results on '"Guadagno, Liberata"'

201. Cure behavior and mechanical properties of structural self-healing epoxy resins

Author

Guadagno, Liberata, Longo, Pasquale, Raimondo, Marialuigia, Naddeo, Carlo, Mariconda, Annaluisa, Sorrentino, Andrea, Vittoria, Vittoria, and Generoso Iannuzzo, Salvatore Russo

Subjects
aircraft materials composites curing of polymers epoxy matrix FTIR mechanical properties self-healing materials
Published
2010

224. Nanotechnologies for Multifunctional Materials

Author

Guadagno, Liberata, Gorrasi, G., Naddeo, Carlo, Tammaro, Loredana, Romeo, V., Bugatti, V., Raimondo, Marialuigia, Vertucci, L., Sorrentino, A., and Vittoria, V.

Published
2007

228. Experimental evaluation and modeling of thermal conductivity of tetrafunctional epoxy resin containing different carbon nanostructures.

Author

Romano, Vittorio, Naddeo, Carlo, Vertuccio, Luigi, Lafdi, Khalid, and Guadagno, Liberata

Subjects
THERMAL conductivity, EPOXY resins, NANOSTRUCTURES, NANOCOMPOSITE materials, MULTIWALLED carbon nanotubes
Abstract

This study attempts to investigate the thermal conductivity behavior of epoxy nanocomposites containing different types of nanofillers, such as 1-D Multiwall Carbon Nanotubes (MWCNTs) and 2-D predominant shape of Exfoliated Graphite nanoparticles (EG) at loading level from 0.25 to 3% wt. For all the analyzed epoxy nanocomposites calorimetric investigation shows that EG nanoparticles accelerate the curing process of the epoxy resin. Thermal conductivity measurements show that this acceleration is directly related to the better heat conduction obtained through the incorporation of EG in the epoxy matrix. The thermal conductivity of epoxy nanocomposites filled with EG, unlike of epoxy nanocomposites containing MWCNTs, increases significantly with increasing content of nanofiller. An increase in thermal conductivity of ∼ 300% has been detected for a filler percentage of only 3%wt of EG. The application of Deng-Zheng micromechanical model has proven to be very effective in predicting analytically the thermal conductivity of the analyzed nanocomposites. POLYM. ENG. SCI., 57:779-786, 2017. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Published
2017
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229. New structure of diamine curing agent for epoxy resins with self-restoration ability: Synthesis and spectroscopy characterization.

Author

Raimondo, Marialuigia, Guadagno, Liberata, Naddeo, Carlo, Longo, Pasquale, Mariconda, Annaluisa, and Agovino, Anna

Subjects
*DIAMINES, *EPOXY resins, *DAPSONE, *CHEMICAL synthesis, *AERONAUTICAL engineers
Abstract

The development of smart materials in aeronautical structures consisting of compounds based on epoxy resins having self-repair capability has been hampered by some criticalities. One of the main critical points is related to the impossibility to use primary amines (e.g.: 4,4′-diaminodiphenyl sulfone, DDS) as hardeners, because they can poison the catalyst responsible for the healing mechanisms. In this paper, the synthesis, characterization and some tests of applicability of a new hardener, the tetramethylated diaminodiphenyl sulfone (tm-DDS), are shown. The tm-DDS is able to rapidly react with epoxy resin, giving a composite material having some characteristics significantly better than composites hardened with different tertiary amines. The new hardener is able to increase the glass transition temperature (Tg) of about 90 °C with respect to the more common hardener, ancamine K54, already used in self-healing epoxy formulations. [ABSTRACT FROM AUTHOR]

Published
2017
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230. Electrical anisotropy controlled heating of acrylonitrile butadiene styrene 3D printed parts.

Author

Guadagno, Liberata, Aliberti, Francesca, Longo, Raffaele, Raimondo, Marialuigia, Pantani, Roberto, Sorrentino, Andrea, Catauro, Michelina, and Vertuccio, Luigi

Subjects
*HEATING control, *CARBON nanotubes, *THERMISTORS, *ELECTROMAGNETIC interference, *FUSED deposition modeling, *ACRYLONITRILE, *ATOMIC force microscopy, *SCANNING tunneling microscopy, *ATOMIC force microscopes
Abstract

[Display omitted] • Fused Filament Fabrication (FFF) 3D Printed artefacts were designed with different multi-scale configurations of the internal conductive pathways. • Electrothermal conduction paths through the sample were controlled by changing the printing parameters. • Tunneling Atomic Force Microscope (TUNA) provides direct information on the electrically conductive paths essentially composed of aligned Carbon Nanotubes. • The raster angle affects the electrical conductivity of the artefact printed parts and their heating. This study proposes a simple method to produce three-dimensional (3D) manufacts with multiscale configurations and controlled electrical resistivity. 3D printed artefacts, based on acrylonitrile butadiene styrene and carbon nanotubes (CNTs), are obtained by fused filament fabrication. Highly orientated conductive pathways are achieved in the sample by selecting appropriate printing parameters. Scanning electron microscopy and tunnelling atomic force microscopy confirm that the conductive traces are essentially composed of aligned CNTs. The printing process determines an increase in the electrical conductivity from 6.88 × 10-2 (spooled filament) to 11.9 S/m (printed filament). The orientation of the spatial domains from the macro- to nanoscale is responsible for a decrease in the electrical resistance from 7782 (90° raster angle sample) tο 478 Ω (0° raster angle sample). Appropriate selection of the configuration and dimensions of electrical contacts confers the ability to selectively heat the part when subjected to an electric source. Temperature differences up to 55 °C were obtained in samples printed with a double-angle raster combination by changing the applied voltage from 20 to 40 V. This strategy can be used to fabricate electronic devices, thermistors capable of converting electrical energy to thermal energy, heat exchangers, and shielding for electromagnetic interference in a single step. [ABSTRACT FROM AUTHOR]

Published
2023
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245. Development of a new stable ruthenium initiator suitably designed for self-repairing applications in high reactive environments.

Author

Longo, Pasquale, Mariconda, Annaluisa, Calabrese, Elisa, Raimondo, Marialuigia, Naddeo, Carlo, Vertuccio, Luigi, Russo, Salvatore, Iannuzzo, Generoso, and Guadagno, Liberata

Subjects
RUTHENIUM, METATHESIS reactions, GUMS & resins, POLYMERS, ALKENES
Abstract

A stable initiator for ROMP reactions, suitably designed to be embedded in structural resins, has been synthetized. It rapidly polymerizes cyclic olefins in reactive environments. The thermal stability and chemical inertness towards oxirane rings allow its employment in the form of molecular complex in epoxy precursors thus reducing the amount of initiator in structural self-healing materials of 90% wt/wt, simultaneously preserving the catalytic activity at high temperatures (180–200 °C) also in presence of the aromatic primary amine (DDS). NMR and FTIR spectroscopy highlighted a relevant initiator stability able to fulfill industrial requirements. Self-healing efficiency has been found to be 103%. [ABSTRACT FROM AUTHOR]

Published
2017
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