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21.
《International Journal of Hydrogen Energy》2022,47(10):6755-6766
Mg-based hydride is a promising hydrogen storage material, but its capacity is hindered by the kinetic properties. In this study, Mg–Mg2Ni–LaHx nanocomposite is formed from the H-induced decomposition of Mg98Ni1·67La0.33 alloy. The hydrogen capacity of 7.19 wt % is reached at 325 °C under 3 MPa H2, attributed to the ultrahigh hydrogenation capacity in Stage I. The hydrogen capacity of 5.59 wt % is achieved at 175 °C under 1 MPa H2. The apparent activation energies for hydrogen absorption and desorption are calculated as 57.99 and 107.26 kJ/mol, which are owing to the modified microstructure with LaHx and Mg2Ni nanophases embedding in eutectic, and tubular nanostructure adjacent to eutectic. The LaH2.49 nanophase can catalyze H2 molecules to dissociate and H atoms to permeate due to its stronger affinity with H atoms. The interfaces of these nanophases provide preferential nucleation sites and alleviate the “blocking effect” together with tubular nanostructure by providing H atoms diffusion paths after the impingement of MgH2 colonies. Therefore, the superior hydrogenation properties are achieved because of the rapid absorption process of Stage I. The efficient synthesis of nano-catalysts and corresponding mechanisms for improving hydrogen storage properties have important reference to related researches. 相似文献
22.
《Ceramics International》2021,47(22):31713-31723
Continuous carbon-fibre-reinforced Cs-geopolymer composite (Cf/CsGP) were prepared, and its in-situ conversion was investigated during high-temperature treatments. The effect of treatment temperature on the thermal evolution process and mechanical properties of the resulting products were systematically evaluated. The results indicated that the crystallization temperature of Cf/CsGP composite was considerably delayed because the amorphous structure of carbon fibres was not conducive as a nucleation substrate for pollucite derived from the CsGP matrix. Moreover, the integrity of the corresponding resulting products derived from the Cf/CsGP composite were damaged due to thermal shrinkage that occurred during the high-temperature treatment process. When treatment temperature was ≤1200oC, the mechanical properties of the corresponding products exhibited an upward trend, which was ascribed to the improvement of the densification degree of the resulting composite and well interface-bonding state between carbon fibres and pollucite. However, the mechanical properties of the resulting composites decreased with the treatment temperature continued increased from 1200 to 1400oC. This phenomenon was attributed to the impairment of fibre properties caused by interfacial reactions. 相似文献
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Xiaojin Li Quanxin Yang Hongliang Liu Yingying Ren Xuping Wang Pengfei Wu 《Ceramics International》2021,47(9):11989-11992
We observe enhancements of both conductive and dielectric properties under UV illumination by using a ferroelectric absorber, potassium tantalate niobate (KTa1-xNbxO3, KTN). The UV-generated electron-hole pairs weaken the intrinsic ferroelectric polarization while enhance the conductive property. The UV-induced heat effect causes the enhancement of the dielectric property. The results are further confirmed by the maximal rectification ratio which shows an opposite trend between the direct heating process and the UV illumination. Our results are useful for better understanding of ferroelectric properties under UV illumination and the development of new optoelectronic devices. 相似文献
26.
综述了近几年国内外改性聚乳酸(PLA)发泡技术的研究进展,针对PLA在发泡方面熔体强度和结晶性能的不足,介绍了通过加入扩链剂、交联剂、成核剂、纤维和其他聚合物等物质来改善PLA发泡性能的方法、效果和机理;最后,对改性聚乳酸发泡技术的未来发展进行了展望。 相似文献
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To improve the hydrophobicity of bagasse hemicellulose-based films, glutaraldehyde was applied when preparing films of original and cationic bagasse hemicellulose with the addition of polyvinyl alcohol and sorbitol. The results showed that the cationic modification could increase the hydrophobicity of the hemicellulose-based film, and the hydrophobicity of hemicellulose-based films crosslinked with glutaraldehyde also increased. However, cationic modification of hemicellulose decreased the stress of the hemicellulose-based film. While crosslinking with glutaraldehyde increased the stress of both the original and cationic hemicellulose-based films. Macrophotography indicated that the film formability of the original hemicellulose was better than that of cationic hemicellulose. Through SEM observation, the degree of bonding of different components of the films was found to be increased due to crosslinking with glutaraldehyde. The crosslinking reaction between glutaraldehyde and hemicellulose was further confirmed by FT-IR spectroscopy. 相似文献
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This paper describes a facile method to control the morphology of polymer colloids and the architecture of polymer film via miniemulsion polymerization. By taking advantage of cyclization between the symmetrical diacrylate cross-linker hexamethylene diacrylate (HDDA) and the pendent vinyl in colloidal particles, the morphology of polymer colloids and the architecture of the after-formed polymer film were able to be well controlled by tuning the loading of cross-linker HDDA and crosslinking time. Four kinds of polymer colloid morphologies and four kinds of film architecture (honeycomb, close-packed, loose-packed, and enhanced-honeycomb) were characterized by TEM. The film formation mechanisms behind them were proposed based on the special and interesting results including Z-average size of the colloidal particles, Mc (molecular weight between crosslinking points) and mechanical properties of polymer film. Our results highly suggested that the morphology of polymer colloids and the polymer film architecture together determine the adhesive properties of the colloidal polymer film. The best of 180°-peel resistance, T-peel resistance and shear resistance of the polymer films were 138.12 N/25 mm, 40.98 N/25 mm and 25.72 N/cm2 at 2.0 phm, 2.0 phm and 0.4 phm with the same crosslinking time of 90 min, respectively. The proposed method is promising to be scaled up for industrial production due to its well adaptability. 相似文献