Browsing by Author "Ao, Xiang"
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Item MXene multi-functionalization of polyrotaxane based PCMs and the applications in electronic devices thermal management.(Nano Materials Science, 2024) Yin, Guang-Zhong; López, Alba Marta; Collado, Ignacio; Vázquez López, Antonio; Ao, Xiang; Hobson, Jose; Prolongo, Silvia G.; De-Yi, WangThe aim of this work was to improve the thermal conductivity and electromagnetic shielding of the leakage proof phase change materials (PCMs), in which a polyrotaxane (PLR) was used as a support material to encapsulate PEG 1k or PEG 6k and MXene as multi-functional filler. The PCMs can be processed conveniently by a hot press and the PEG 1k containing samples showed excellent flexibility. We conducted a systematic evaluation of the phase transition behavior of the material, thermal conductivity and electromagnetic shielding performance tests. Notably, the PCMs achieved a high enthalpy values (123.9–159.6 J/g). The PCMs exhibited an increase of 44.3 %, and 137.5 % in thermal conductivity values with higher MXene content (5 wt%) for PLR-PEG6k and PLR-PEG1k, respectively, and show high shape stability and no leakage during and after phase transition. The introduction of MXene can significantly improve the electromagnetic shielding performance of PCM composites. Typically, higher conductive samples (samples which contain high MXene contents) offer a higher EMI SE shielding, reaching a maximum of 4.67 dB at 5.6 GHz for PLR-1K-MX5. These improvements solve the main problems of organic PEG based PCMs, thus making PLR-PEG-MXene based PCMs good candidates for thermoregulators of both solid-state disks and smart phone. It is worth pointing out that the sample PLR-1k-MX5 can decrease 4.3 °C of the reference temperature during cellphone running. Moreover, the temperature of the protecting sheet in the simulated solid state disk with PCM was significantly lower (showing a decreasing of 7.9 °C) compared with the blank sample.Item PLA aerogel as a universal support for the typical organic phase change energy storage materials.(Journal of Energy Storage, 2023) Yin, Guang-Zhong; Yang, Xiao-Mei; López, Alba Marta; Ao, Xiang; Wang, Mei-Ting; García Molleja, Javier; De-Yi, WangWe first prepared Polylactic acid (PLA) aerogels with high porosity based on a facile and efficient thermal induced phase separation technique. In view of the excellent internal nano structure of PLA aerogel, high porosity and suitable interfacial affinity, it was selected as a support material to encapsulate four common organic phase change materials (PCMs), thereby preparing anti-leakage, shape-stable and sustainable PCMs with ultra-high latent heat (178.9–224.9 J g−1). PLA aerogel encapsulated PCMs perform high enthalpy efficiency (>92 %), which may benefit from the highly internal compatible nanostructure of PLA. Thermally conductive fillers (Boron nitride and Graphene nanoplatelet) were introduced to improve thermal conductivity. An important factor of PLA aerogel as a universal encapsulation matrix is analyzed based on the solubility parameters and Flory-Huggins parameters. The application cases of smart container and thermal regulation in confined spaces further prove the practical application value in the thermal regulation and energy saving area.Item Polyrotaxane based leakage-proof and injectable phase change materials with high melting enthalpy and adjustable transition temperature.(Chemical Engineering Journal, 2022) Yin, Guang-Zhong; López, Alba Marta; Yang, Xiao-Mei; Ao, Xiang; Hobson, Jose; De-Yi, WangIn this work, a series of advanced phase change materials (PCMs) were fabricated by using polyrotaxane (PLR) as supports for encapsulating poly (ethylene glycol) (PEG). Phase-change enthalpy is mainly regulated by the PEG contents, whereas phase change temperature is controlled by PEG molecular weight. All PCMs have good form stabilities due to the good compatibility between PLR and PEG, and supporting ability of PLR. Given that the PLR support itself has phase-transition properties, the resulting composites have high phase change enthalpies (116.1–162.2 J g -1) and very high enthalpy efficiency (>100%). It is a green and efficient preparation method because the whole preparation process did not involve organic solvents, and the material was prepared at room temperature. In addition, the obtained PCMs can be easily extruded and re-molded, which provides technical premise and convenience for the large-scale applications. As a typical application example, the PCMs showed its significant advantages in simulated solid-state disk model temperature regulation, which fully demonstrates the practical and superior application value of the PCMs in the field of thermal management for electronic devices.Item Synergistic Effect of Cerium Oxide for Improving the Fire-Retardant, Mechanical and Ultraviolet-Blocking Properties of EVA/Magnesium Hydroxide Composites.(Materials, 2022) Hobson, Jose; Yin, Guang-Zhong; Yu, Xiaoli; Zhou, Xiaodong; Gonzalez Prolongo, Silvia; Ao, Xiang; De-Yi, WangRare earth oxide particles have received important attention in recent years, and due to the wide diversity of promising applications, the need for this kind of material is predicted to expand as the requirements to use the current resources become more demanding. In this work, cerium oxide (CeO2) was introduced into ethylene-vinyl acetate (EVA)/magnesium hydroxide (MDH) composites for enhancing the flame retardancy, mechanical properties and anti-ultraviolet aging performance. The target EVA/MDH/CeO2 composites were prepared by extrusion and injection molding, and the effects of the addition of the CeO2 were explored by thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), limiting oxygen index (LOI), UL-94, cone calorimetry test, and anti-ultraviolet aging test. Typically, the incorporation of the CeO2 allows a significant increase of the elongation at break and Young’s modulus compared with EVA/MDH by 52.25% and 6.85%, respectively. The pHRR remarkably decreased from 490.6 kW/m2 for EVA/MDH to 354.4 kW/m2 for EVA/MDH/CeO2 composite. It was found that the CeO2 presents excellent synergism with MDH in the composites for the anti-UV properties in terms of mechanical properties preservation. Notably, the combination of CeO2 with MDH is a novel and simple method to improve the filler–polymer interaction and dispersion, which resulted in the improvement of the mechanical properties, flame retardancy and the anti-ultraviolet aging performance of the composites.