Abstract Conventional plain organic or inorganic shell for microcapsules has their own drawbacks, the organic shell has defects in thermal conductivity and stability; while the compactness and coverage of inorganic shell are not satisfactory. Herein, a novel approach to synthesis of organic–inorganic composite double‐layer shell phase change microcapsule (DLSPCM) is proposed, which is achieved by forming inorganic outer shell on the surface of organic shell via atomic layer deposition (ALD). Taking the pristine microcapsule with paraffin core and melamine formaldehyde (MF) shell as an example, MF‐ZnO composite double‐layer shell (DLS) is formed in this paper. The melting enthalpy of DLSPCM obtained by 100 ALD cycles is 159.7 J g −1 , which is only 12.1 J g −1 lower than that of paraffin @ MF microcapsules (control sample), while the thermal conductivity of DLSPCM surges by 77.8%, and the thermal energy storage ability and thermal regulation performance are basically maintained. After 900 thermal cycles, the heat storage capacity of DLSPCM obtained by 100 ALD cycles decreased by only 3%. Besides, the photocatalytic performance and antibacterial activity of ZnO‐reinforced DLSPCM are further confirmed. The successful design of DLSPCM via ALD is prospective for the encapsulation, modification, and reinforcement of phase change microcapsules.
Abstract A novel composite yarn was prepared by simple sizing coating using polyester (PET) as core yarn and polyvinyl butyral (PVB) and zirconium carbide (ZrC) suspension as slurry. The scanning electron microscope results revealed the core–shell structure of the composite yarn and ZrC particles deposited on surface coating successfully. The maximum near‐infrared absorption rate of the fabric made of PET/PVB/ZrC composite yarn reached 96.42%. The test showed that when exposed to infrared light (dominant wavelength 950 nm), the surface temperature of the composite yarn rose more quickly than that of pure PET yarn. The photothermal conversion property of the composite yarn reached the best when PET yarn was treated in 4 wt% PVB solution with 5 wt% ZrC content. The composite yarn also exhibited good light‐to‐heat performance in real environment. In addition, PVB/ZrC coating provided the composite yarn excellent ultraviolet (UV) protection (UPF 50+) and produced little effect on thermal stability. Durability tests of PET/5%PVB/4%ZrC composite yarn verified pretty good washing resistance of near‐infrared absorption and UV protection properties of the composite yarn. This work provides a simple and economical method for preparing multifunctional composite yarn.
Ultra-fine grain ZK60 magnesium alloys were fabricated separately by conventional single-step equal channel angular pressing (ECAP) processing and two-step ECAP processing. The microstructures and mechanical properties of the ZK60 magnesium alloys were investigated by optical microscopy,scanning electron microscopy,transmission electron microscopy and tensile test,and the texture was measured by XRD. The results show that,two-step ECAP is more effective in grain refinement than single-step ECAP process due to the lower deformation temperature. The grain size is refined to 0.8 μm after being processed with treatment of (240 ℃,4 passes)+(180 ℃,4 passes). Compared with the as-received ZK60 alloy,the single-step ECAP processed alloy has lower strength but higher elongation to failure. The decrease in strength is mainly ascribed to texture softening. However,after two-step ECAP process,the strength is improved due to the enhancement of fine grain strengthening and substructure strengthening.
Surface passivation using aminopropyl-functionalized siloxane is proposed via a post-synthesis ligand exchange reaction. The near-unity photoluminescence quantum yield (PLQY) is explained by more efficient surface passivation, which is confirmed by transient PL measurements. Alternatively, the siloxane can be introduced during the hot-injection synthesis, and a thicker SiO2 shell structure is formed on the surface of nanocrystals (NCs), which leads to agglomeration and degrades optical properties. The low-temperature ligand exchange reaction lends precision process control; thereby, an optimized PLQY of 99% is achieved. Moreover, the emission wavelength of the siloxane passivated CsPbBr3 can be modulated via halide exchange for highly saturated and stable green emissions. The stability of these NCs is first ascribed to the siloxane moiety. Siloxane passivated CsPbI3 NCs were also prepared with bright red emission. A wide color gamut of 134.9% National Television System Committee or 100.7% Rec. 2020 is realized using blue light-emitting diodes together with green and red perovskite NCs. We stress the effect of Cs vacancy repair via the ligand exchange and the essentially monolayer thickness of the ligand shell to ascribe the high performance of these NCs.
As a functional textile, photothermal textile materials are receiving more and more attention. A composite yarn was prepared by coating polyvinyl butyral/zirconium carbide/alumina oxide on the surface of polyester yarn through a sizing coating method with the aim to provide a textile substrate with controlled photothermal efficiency. The Box–Behnken design combined with response surface analysis and regression method was used to study the effects of input variables (polyvinyl butyral, zirconium carbide and alumina oxide concentration) on the temperature of the fabric made of polyester/polyvinyl butyral/zirconium carbide/alumina oxide composite yarn under infrared light irradiation. It was found that the effect of polyvinyl butyral and zirconium carbide content on the fabric surface temperature was more significant than that of alumina oxide content. The established regression model could predict the response value (fabric temperature) precisely. The optimal conditions for preparing the polyester/polyvinyl butyral/zirconium carbide/alumina oxide composite yarn were obtained by response surface analysis: 5.9% polyvinyl butyral, 5% zirconium carbide and 0.5% alumina oxide. The structure and properties of the yarn prepared under the optimal conditions were characterized. The results showed zirconium carbide and alumina oxide deposited on surface coating without obvious deterioration of thermal stability and tensile strength. The near-infrared light absorption rate of the composite yarn reached 96.71% and its surface temperature reached 104.0°C after 180 s irradiation under an infrared lamp. The photothermal temperature can still reach 101.5°C after 20 cyclings. The excellent photothermal conversion capacity indicates the polyester/polyvinyl butyral/zirconium carbide/alumina oxide yarn can realize solar energy utilization and be applied in heat management textiles.
Taking the southern approach bridge of Yudong Yangtze River Bridge as the research object,which applies the cast-in-place construction technology to continuous box girder on Bailey beams stent,the stent-reaction forces under different conditions of cast-in-place box girder are obtained through Dr 3.0 bridge finite element analysis software.Then Bailey truss structure model established by ANSYS 9.0 finite element analysis software is applied to check the spatial stability in the construction of Bailey truss structure.The relevant stability coefficients and the corresponding instability modes are obtained.Eventually,relevant recommendations to prevent such instability of Bailey stent are given.
This article explored the conditions and application of the minimal measure between the straight-line and the axis,and popularized it to three-dimensional space,and thus conditions and some related applications of the minimal measure between the straight line(plane) and the coordinate axis(coordinate surface) are obtained.
Talent accumulation plays a vital role in improving the comprehensive benefit of Intelligent Transportation System (ITS). Based on literature reviewing, this research analyzes the synergistic mechanism between talent accumulation and the effect of ITS. According to the synergistic model, the degree of synergy between talent accumulation and the effect of ITS has been tested by using related statistical data. The results reveals the developing tendency and the level of synergy between talent accumulation and the effect of ITS. In addition, the results have both theoretical and practical implications for strengthening the effect of talent accumulation and improving the comprehensive benefit of ITS effectively.
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