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Li Dong Guo Enyan Lu Qifang Ji Xueyang Wei Mingzhi 《Journal of Solid State Electrochemistry》2017,21(8):2313-2320
Journal of Solid State Electrochemistry - The one-dimensional graphene/TiO2 composite nanofibers with the unique microstructures have been successfully synthesized via an efficient method and... 相似文献
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Poly(vinyl alcohol)/melamine phosphate composites (PVA/MP) as a novel halogen‐free, flame‐retardant foam matrix were prepared through thermal processing, and then their thermal stability and flame retardancy were investigated by thermo‐gravimetric analysis, micro‐scale combustion calorimeter, cone calorimeter, vertical burning test, and limiting oxygen index (LOI) test. It was found that the thermal stability and combustion properties of the PVA/MP composites could be influenced by the addition of MP. Compared with the control PVA sample (B‐PVA), in the PVA/MP (75/25) composites, the temperature at 5% mass loss (T5%) decreased about 10°C, the residual chars at 600°C increased by nearly 27%, the temperature at the maximum peak heat release rate (TP) shifted from 292°C to 452°C, and the total heat released and the heat release capacity (HRC) decreased by 28% and 14%, respectively. Moreover, the PVA/MP composites could reach LOI value up to 35% and UL94 classification V‐0, showing good flame retardancy. At the same time, both Fourier transform infrared and X‐ray photoelectron spectroscopy spectra of the residual chars from the PVA/MP composites demonstrated that the catalytic effect of MP on the dehydration and decarboxylation reactions of PVA, and the chemical reactivity of MP during the chars‐forming reactions could be used to account for the changed thermal stability and flame retardancy of the PVA/MP composites. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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A side‐chain polysiloxane cholesteric liquid crystalline elastomer (ChLCE) with binaphthalene derivate as crosslinkings and cholesterol derivate as liquid crystalline monomers was designed and synthesized. A binaphthyl chiral dopant (CD) was synthesized as well. The chemical structures and liquid crystalline properties of the ChLCE and the CD were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, element analyses, differential scanning calorimetry and polarizing optical microscopy measurements. The helical twisting power of the ChLCE exhibited a turning point with changing temperature and was smaller than that of the CD. In addition, the effect of the ChLCE on phase transition temperatures and thermal‐optical properties of a liquid crystal that show smectic A (SmA)‐cholesteric (Ch) phase transition was studied. Worthily, the testing of the reflection wavelength with changing temperature suggested that the adding of the ChLCE in liquid crystals that show SmA‐Ch phase transition can expedite their SmA‐Ch transition. In addition, the network structure of the ChLCE may play a significant role in the accelerating of the transition. These properties provided theoretical and experimental foundations for applying ChLCE in thermally sensitive liquid crystal devices requiring fast response, such as thermally controllable windows, materials and displays. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Considering intrinsic properties of conjugated polyfluorenes and special functions of porous polymers, synthesis of fluorinated porous poly(spirobifluorene) via direct C?H arylation polycondensation is explored. Owing to the contorted structure and cross-linking nature, the obtained polymer FPSBF shows permanent porosities with Brunauer–Emmett–Teller specific surface area up to 700 m2 g?1 and exhibits a narrow pore size distribution with the dominant pore size at about 0.63 nm, which is more suitable for adsorption of small gas molecules. Based on the measured gas physisorption isotherms with pressure up to 1.13 bar, the obtained polymer shows good uptaking capacities for hydrogen (1.30 wt% at 1.0 bar and 77 K) and methane (4.80 wt% 1.0 bar and 273 K). Moreover, FPSBF has significant adsorption selectivity for CH4 against N2 and the estimated ideal adsorption selectivity ratio is up to 30/1 at 1.0 bar and 273 K, which makes the material possess potential application in gas separation. 相似文献