Examinando por Autor "G. Prolongo, Silvia"

Mostrando 1 - 4 de 4

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.
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.