Examinando por Autor "Prolongo, Silvia G."

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4D-Printed Resins and Nanocomposites Thermally Stimulated by Conventional Heating and IR-Radiation
(ACS, 2021) Cortés, A.; Aguilar, Jose L.; Cosola, A.; Fernández Sanchez-Romate, Xoan Xosé; Jiménez-Suárez, A.; Sangermano, M.; Campo, M.; Prolongo, Silvia G.
The shape memory (SM) capabilities of nanocomposites based on two photocurable acrylated/methacrylated resins, doped with carbon nanotubes (CNTs), and manufactured by digital light processing 3D printing were investigated. The mechanical properties and glass transition temperature (Tg) can be tailored in a broad range by varying the weight ratio of the two resins (Tg ranging from 15 to 190 °C; Young’s modulus from 1.5 to 2500 MPa). Shape fixity (SF) and recovery (SR) ratios are strongly influenced by the temperature being significantly higher at temperatures close to the Tg. The results confirm that the SF strongly depends on the stiffness of chain segments between cross-linking points, whereas the SR mainly depends on the cross-link density of the network. CNT addition barely affects the SF and SR in the conventional oven, whereas the recovery speed using IR heating is significantly increased for the doped nanocomposites due to their higher IR absorbance.
Microhardness and wear behavior of nanodiamond-reinforced nanocomposites for dental applications
(Wiley, 2024-10-04) Moriche, Rocío; Artigas-Arnaudas, Joaquín; Chetwani, Bhanu; Sánchez, María; Campo, Mónica; Prolongo, Margarita G.; Rams, Joaquín; Prolongo, Silvia G.; Ureña, Alejandro
In polymer-based dental composites, wear is a three-body wear system mainly abrasive, because of the food particles and wear products suspended in the oral cavity, which are transferred to the microcavities of the surface of the replacements. Due to this fact, the incorporation of nanodiamond as reinforcement in these polymer–matrix composites, which promotes the creation of a solid lubricant tribofilm surface could be advantageous. With the reinforcement of nanodiamonds, BisGMA/TEGDMA-based composites increase their microhardness by 95%–420%. A maximum hardness exceeding 65 HV is achieved with a reinforcement of 3.2 wt%. The specific wear rate of neat BisGMA/TEGDMA is near 10−4 mm3/Nm and the Archard's coefficient is 2.6 × 105. The incorporation of a content of 1.6 wt% ND is enough to cause a diminution of ~78% in the friction coefficient and a reduction of the specific wear rate and Archard's coefficient of ~50%. Nevertheless, the addition of relatively high contents reduces the effectiveness of photoinitiation and photocuring, which is related to the scattering and absorption of light radiation by ND. This causes a significant decline in elastic properties starting at 50 μm from the surface. Highlights Photocuring polymer resin was successfully reinforced with nanodiamonds. Microhardness increases from 95% up to 420%, close to commercial composites. Friction coefficient and wear rate are reduced with 1.6 wt% nanodiamonds. High levels of reinforcement reduce the effectiveness of photocuring.
Smart electroactive self-repairable coating involving end-of-life aircraft prepregs by mechanical recycling
(Elsevier, 2024-09) Espeute, Emma; Martinez-Diaz, David; Vázquez Sánchez, Pablo; Martín, Zulima; Rosario, Gilberto Del; JIménez-Suárez, Alberto; Prolongo, Silvia G.
The environmental impact of the Carbon Fiber Reinforced Polymers (CFRPs) industry, particularly due to waste generation during manufacturing and end-of-life phases, is compelling major industrial entities to reconsider a circular economy approach for their materials and to comply with emerging regulations. This study explores the potential of recycled carbon fibers (rCFs) derived from the mechanical recycling of prepreg waste. Mechanical recycling was selected for its cost-effectiveness and moderate environmental impact, recovering short rCFs with lengths below 200 μm. These rCFs, which retain excellent electrical properties, are incorporated into an epoxy matrix with Polycaprolactone (PCL) to create a multifunctional coating with self-healing capabilities. The resulting composite material exhibited significant improvements in electrical conductivity, achieving up to 16.50 S/m, and demonstrated effective Joule effect heating, exceeding 200 °C with 20 V applied for a composite containing 15 wt% rCF. The self-healing efficiency for surface cracks, activated by the Joule effect, reached 80–90 %, resulting in a 99 % reduction in energy consumption compared to conventional oven heating. Notably, the self-healing mechanism was characterized in real-time within a scanning electron microscope for the first time, providing a comprehensive evaluation of the process. This innovative coating offers promising applications in aviation for anti-icing, deicing, and maintenance reduction, as well as in residential settings as an energy-efficient floor heating solution. This research underscores the potential of mechanically recycled CFRPs to produce high-value, sustainable materials, promoting a circular economy and reducing the environmental footprint of the aeronautical sector