RESUMEN
Though nanomaterials based on carbon have been widely used for the preparation of high-performance polymeric nanocomposites, there are few works focused on the effect of carbon nanoparticle morphology on the performance of corresponding polymer nanocomposites. Therefore, four representative carbon nanoparticles, including fullerene, carbon nanotubes, graphene, and carbon black incorporated poly(styrene-b-isoprene-b-styrene) (SIS) elastomer nanocomposites were fabricated using the solvent casting method. In addition, the effect of carbon nanoparticle morphology on the rheological, mechanical, electrical, and thermal properties of the obtained polymeric nanocomposites was systematically investigated. The results showed that the shape of carbon nanoparticles has a different effect on the properties of the obtained elastomer nanocomposites, which lays the foundation of carbon nanoparticle screening for high-performance polymer nanocomposite construction.
RESUMEN
A simple scheme of selective lithium leaching by direct oxidation was proposed. The thermodynamic feasibility of this new method was verified by the E-pH diagram of the Li-Mn-H2O system. Sodium persulfate Na2S2O8 was selected as the oxidant to oxidize LiMn2O4 to MnO2, and subsequently, lithium was de-intercalated from the crystal lattice. The experimental results show that under the optimum conditions, 97% of Li is released into the solution in 120 min, while almost all the Mn remains in the leaching residue. The kinetic study results suggest that selective leaching of Li is controlled by a chemical reaction according to the Avarami model. Furthermore, XRD, XPS, and FT-IR spectroscopy were used to investigate the leaching mechanisms. The content of the LMO phase decreases gradually while the MnO2 phase increases with the lithium extraction, but the spinel structure of lithium manganate is not damaged throughout the process. Finally, a closed-loop process for recycling spent lithium manganate batteries was proposed, which is also suitable for recycling other types of spent LIBs.
RESUMEN
Silica aerogels are attractive materials for various applications due to their exceptional performances and open porous structure. Especially in thermal management, silica aerogels with low thermal conductivity need to be processed into customized structures and shapes for accurate installation on protected parts, which plays an important role in high-efficiency insulation. However, traditional subtractive manufacturing of silica aerogels with complex geometric architectures and high-precision shapes has remained challenging since the intrinsic ceramic brittleness of silica aerogels. Comparatively, additive manufacturing (3D printing) provides an alternative route to obtain custom-designed silica aerogels. Herein, we demonstrate a thermal-solidifying 3D printing strategy to fabricate silica aerogels with complex architectures via directly writing a temperature-induced solidifiable silica ink in an ambient environment. The solidification of silica inks is facilely realized, coupling with the continuous ammonia catalysis by the thermolysis of urea. Based on our proposed thermal-solidifying 3D printing strategy, printed objects show excellent shape retention and have a capacity to subsequently undergo the processes of in situ hydrophobic modification, solvent replacement, and supercritical drying. 3D-printed silica aerogels with hydrophobic modification show a super-high water contact angle of 157°. Benefiting from the low density (0.25 g·cm-3) and mesoporous silica network, optimized 3D-printed specimens with a high specific surface area of 272 m2·g-1 possess a low thermal conductivity of 32.43 mW·m-1·K-1. These outstanding performances of 3D-printed silica aerogels are comparable to those of traditional aerogels. More importantly, the thermal-solidifying 3D printing strategy brings hope to the custom design and industrial production of silica aerogel insulation materials.