Yuhao Wu,Shengming Zhang,Yixiao Yu,Chengzhen Meng,Rongkai Wang,Chaosheng Wang,Huaping Wang,Peng Ji
Phase change fiber, as an intelligent fiber material used in passive thermal management, can balance the temperature of the microenvironment near human skin. However, the traditional blending method makes phase change material prone to leakage during the processing and applications. Herein, this work introduces the phase change material PTMEG into the polyamide 6 (PA6) chain through melt polymerization to prepare a series of PA6-based poly(amide-ether) copolymers. Copolymers exhibit an obvious microphase separation structure, with the PA6 segments and the PTMEG segments can form independent crystalline and amorphous regions. PTMEG in copolymers through polymerization method exhibits better thermal stability compared with the blended way, which effectively solves the leakage problem of phase change materials. The copolymers can be directly melt-spun (1500 m/min) to prepare PA6-based phase change fibers. The fiber can maintain excellent mechanical properties (breaking strength of 2.12 cN/dtex). Meanwhile, the crystallization enthalpy and melting enthalpy of the PTMEG in the fiber are 10.59 J/g and 12.44 J/g, respectively. The thermal management time of the fiber in the hot environment is 349 s, and the maximum temperature difference is lower 5.6 ℃ from the PA6 fiber. In addition, the exothermic duration in a cold environment is 536 s, and the maximum temperature difference is higher 1.1 °C from the PA6 fiber. Meanwhile, the thermal enthalpy of the fiber remained stable (fluctuation within 2 %) after 20th thermal cycles, and the loss rate is less than 2 % after washing at 25 ℃, 50 ℃ and 90 ℃. The fiber exhibits good thermal stability, water washability and cyclic stability. Preparation of high enthalpy polymers directly by copolymerization will provide new ideas for phase change fibers for apparel.
Tunable surface amphiphilic polypropylene (PP) fibers and textiles with multi-grooved hydrophilic micro-structures have been prepared through a commercially scalable segmented pie bicomponent fiber melt spinning and post-treatment process. It was demonstrated that the molecular implantation of a modified polyvinyl alcohol (PVA) macromolecular chains onto the PP interface/interphase during the bicomponent melt-spinning process was responsible for the hydrophilicity inside the micro-channels (micro-groves) of the PP fibers. These hydrophilic channels brought about super capillary wicking effect through the PP fibers and fabrics that is much amplified than previous technologies to functional treatment of the fibers and fabrics via environmentally friendly aqueous processes. In aqueous dyeing treatment, for example, these multi-grooved novel amphiphilic fibers demonstrated a practical solution to the well-known dilemma that PP fiber is essentially impossible to dye due to its inherently low surface energy. Additionally, there is a great promise to expanded the amphiphilic PP to higher-value functionalities and wider-field applications.
Magnesium hydride (MgH 2 ) has garnered significant attention as a promising material for high-capacity hydrogen storage. However, its commercial application remains challenging due to the high operating temperature and slow reaction kinetics. In this study, melt-spun Ti 45 Cr 40 Nb 15 (with a BCC phase) hydride (designated as TiCrNbH x− MS) was synthesized and used to form a nano-multiphase composite to improve the de-/rehydrogenation properties of MgH 2 through ball milling. The incorporation of TiCrNbH x− MS was shown to significantly enhance the hydrogen de-/rehydrogenation properties of MgH 2 . The MgH 2 + 20 wt% TiCrNbH x− MS composite exhibits an appealing initial dehydrogenation temperature of 163 °C and can absorb hydrogen at room temperature. Notably, it releases 5.8 wt% hydrogen in 700 s at 230 °C and recharges 4.3 wt% hydrogen in just 2 mins at 150 °C. Even after 100 cycles, it retains a reversible hydrogen capacity of 4.98 wt%. Kinetic analysis revealed that the dehydrogenation rate follows the Chou surface penetration model. Microstructural analysis showed that the FCC phase of the melt-spun TiCrNbH x− MS hydride reversibly transformed into the BCC phase during the de-/rehydrogenation process in the composite. Numerous phase interfaces were generated and uniformly dispersed on the MgH 2 surface, providing additional hydrogen diffusion pathways and heterogeneous nucleation sites for Mg/MgH 2 , thereby further improving the hydrogen de-/rehydrogenation kinetics of the system. This study offers valuable insights into the use of multiphase composites to enhance MgH 2 performance.
危险品化学品经营许可证（带存储）