Examinando por Autor "G. Prolongo, Silvia"

Mostrando 1 - 6 de 6

3D printed epoxy-CNTs/GNPs conductive inks with application in anti-icing and de-icing systems
(Elsevier, 2020-12-05) Cortés, Alejandro; Jiménez-Suárez, Alberto; Campo, Mónica; Ureña, Alejandro; G. Prolongo, Silvia
En este trabajo se estudia el desarrollo y caracterización de circuitos conductores impresos en 3D basados en tintas epóxicas dopadas con nanotubos de carbono (CNTs) y/o nanoplaquetas de grafeno (GNPs), que podrían ser utilizados en aplicaciones como circuitos electrónicos, asientos calefactados, sistemas antihielo y deshielo (ADIS) o sistemas de monitorización de la salud estructural (SHM), entre otros. Se ha llevado a cabo un diseño de experimentos (DOE) por el método Taguchi para desarrollar y optimizar un ADIS basado en un circuito impreso en 3D, utilizando una tinta conductora dopada con CNTs/GNPs para conseguir un calentamiento por efecto Joule. El objetivo se basa en alcanzar la temperatura media más alta, que se ha medido mediante análisis termográfico de infrarrojo, teniendo en cuenta también la calidad de los circuitos impresos en 3D. Los factores del DOE han sido el contenido de CNT y GNP, el voltaje aplicado al circuito y su geometría, proponiendo dos diseños alternativos. Finalmente, se ha llevado a cabo un ensayo de deshielo con los parámetros óptimos obtenidos a partir del DOE. Los resultados evidencian la viabilidad del sistema desarrollado, siendo capaz de fundir una capa de hielo de 2,5 mm de espesor en 3 minutos y 30 segundos.
Hardener Isomerism and Content of Dynamic Disulfide Bond Effect on Chemical Recycling of Epoxy Networks
(ACS, 2022) Martinez-Diaz, David; Cortés, Alejandro; Jiménez-Suárez, Alberto; G. Prolongo, Silvia
Nowadays, there is an important concern in the scientific community related to the end-of-life products derived from polymeric matrix composites. In this regard, covalent adaptable networks and, more specifically, the disulfide bond-based ones are a promising approach to develop composite parts able to be dissolved in a specific solvent, thus regaining the continuous fiber reinforcement. In this work, the effect of hardener isomerism, using 2-aminophenyl disulfide (2-AFD) and 4-aminophenyl disulfide (4-AFD), and amine/epoxy ratio (1.0–1.2) was studied to optimize the chemical recycling capabilities at different temperatures. Results confirmed the need for using hardener excesses for dissolving these vitrimers. Networks based on 2-AFD were dissolved in considerably lower times than the 4-AFD ones, which is interesting since the latter one is quite more used for this purpose and currently way more expensive. In this context, a composite laminate, reinforced with six layers of carbon fiber fabric, was manufactured as the proof-of-concept.
Multifunctional coatings based on GNP/epoxy systems: Strain sensing mechanisms and Joule's heating capabilities for de-icing applications
(Elsevier, 2022) Sánchez-Romate, Xoan F.; Gutiérrez, Rodrigo; Cortés, Alejandro; Jiménez-Suárez, Alberto; G. Prolongo, Silvia
Multifunctional coatings based on a GNP/epoxy system have been manufactured and their strain sensing and Joule’s heating capabilities for anti-icing and de-icing applications have been explored. It has been observed that an increase in the GNP content induces a detriment on the gauge factor (from 5.75 at 8% to 2.49 at 12%) due to a lower interparticle distance between nanoparticles, being less sensitive. However, in any case, the GF values at bending conditions are significantly above conventional metallic gauges (which is around 2). On the other hand, the resistive heating is more efficient when increasing the GNP content, as expected, due to a higher number of conducting pathways that allows a more efficient Joule’s heating effect. However, and due to the heterogeneity present at 12% GNP samples due to the much higher viscosity of the mixture during the dispersion process, the 10% ones were selected for a de-icing proof of concept, proving that the ice completely melts after 5 min of applying 200 V. Therefore, the proposed GNP coatings show an outstanding capability for both strain sensing and de-icing purposes by resistive heating, being useful for a wide range of applications.
Novel approach for damage detection in multiscale CNT-reinforced composites via wireless Joule heating monitoring
(Elsevier, 2022) Sánchez-Romate, Xoan F; González, Carlos; Jiménez-Suárez, Alberto; G. Prolongo, Silvia
A novel method for strain and crack propagation monitoring based on Joule heating capabilities of multiscale carbon nanotube reinforced glass fiber composites (GFRP-CNT) is reported. The manufactured GFRP-CNT composites show good Joule heating capabilities with heating rates ranging from 3 to 56 ◦C min− 1 at applied voltages from 30 to 105 V, respectively. Multiscale GFRP-CNT composites present similar tensile strength and Young’s Modulus than conventional GFRP but very enhanced failure strain due to the toughening effect of CNTs. The wireless monitoring via Joule heating shows a very high sensitivity and strain resolution (with values ranging from 0.01 to 0.1%) for early crack initiation and subsequent propagation. Finally, the thermal IR imaging also allows to create a complete mapping of the health of the structure during the whole test, allowing the detection, localization and quantification of early damage and, thus, proving an outstanding potential for Structural Health Monitoring (SHM) applications in comparison to other conventional techniques.
Quality assessment and structural health monitoring of CNT reinforced CFRP and Ti6Al4V multi-material joints
(Elsevier, 2021-11-15) Dasilva, Sara; Jiménez-Suárez, Alberto; Rodríguez, Elena; G. Prolongo, Silvia
Hybrid multi-material joints of titanium alloy (Ti6Al4V) bonded to carbon fibre reinforced polymer (CFRP) are really interesting for lightweight high-performance structures, i.e., aeronautical and marine applications. Co-bonding technique, in which the joining takes place at the same time as the manufacturing of the CFRP, could be a great solution for easy manufacturing fibre metal laminate (FML) and complex structures, or a time saving process. One of the biggest challenges in this type of multi-material structures is to be able to confirm the structural health in service. The present work deals with the use, as matrix, of an epoxy resin reinforced with multiwalled carbon nanotubes (MWCNT) for manufacturing of Ti-CFRP joints by co-bonding. The aim is the structural health monitoring (SHM) of these hybrid structures, enhancing their mechanical properties. The obtained results show an improvement of more than 140% in fracture resistance of the multi-material joints with optimal surface preparation, by incorporating CNT. Furthermore, electrical monitoring makes it possible to discern the quality of the manufactured joints, increasing their reliability and performance. Besides, the ability to localize crack propagation and stresses prior to joint failure has been confirmed, so CNT addition results in a powerful tool for SHM multi-material joints.
Self-Healing Activation by Conventional Resistive Heating through the Addition of Carbon Nanotubes in Epoxy Systems Based on Covalent Adaptable Networks
(ACS, 2023) Gómez-Sánchez, Javier; Fernández Sánchez-Romate, Xoan Xosé; Jiménez-Suárez, Alberto; G. Prolongo, Silvia
A study of the self-healing capabilities of 2-aminophenyl disulfide (AFD)/epoxy systems is carried out. It has been observed that an excess of AFD promotes an increase of both the storage modulus and the glass transition temperature (Tg) due to an increase of the cross-link density. Concerning the self-healing properties, every AFD/epoxy system shows very good healing efficiencies (above 90%) with no prevalent differences among the different stoichiometries. Furthermore, CNT addition induces an increase of the storage modulus when there is no excess of AFD, but no significant effect is observed on the Tg. In addition, the incorporation of these nanoparticles allows thermal activation by the Joule effect. The results of self-healing tests under convective and resistive heating show similar healing efficiencies (all above 94%). Here, the thermal activation by Joule’s heating presents a lower power consumption and allows localized repair, which is very promising for this type of application.