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941.
To prepare the flexible and stretchable electromagnetic shielding (EMS) fabric with environmental stability, this paper uses polytrimethylene terephthalate (PTT) fabric as substrate, the aniline monomer as raw material, hydrochloric acid (HCl) as the doping agent, ammonium persulfate (APS) as the oxidant to produce polyaniline (PANI)/PTT electromagnetic shielding fabric by in-situ chemical polymerization. It studies the influence of APS and HCl concentration on the surface electrical resistance and the absorption loss of electromagnetic shielding fabric. It can be observed that an increasing APS and HCl facilitate the absorption and spread of PANI into PTT fabric to form a conductive network, and improve the absorption loss efficiency, while the excess APS and HCl will hinder the PANI polymerization. The high electrical conductivity and absorption loss of the PANI/PTT fabric are obtained at the concentration of An 0.4 M, APS 0.4 M, HCl 1.25 M, and polymerization reaction time 120 min. Meanwhile, in-situ polymerization of PANI does not introduce new impurities and destroy the molecular structure of PTT. 相似文献
942.
This report is the first to detail the antitumor activity of Acanthopanax brachypus, a species well recognized by eastern folk medicine. Four stilbeniods and nine flavonoids have been isolated from stem bark of the plant. The isolates have been tested for their antitumor activity against selected human cancer cell lines (HgpG-2, MCF-7, K-562, and A-549). Even though three of the compounds have shown high to moderate cytotoxicity against certain cell lines (IC50 of 4.5 to 6.5 μg/mL), in most of the experiments little or no anticancer activity has been revealed. 相似文献
943.
Estimation of the critical rate of temperature rise for thermal explosion of nitrocellulose using non-isothermal DSC 总被引:1,自引:0,他引:1
Huiya Wang Hai Zhang Rongzu Hu Ergang Yao Pengjiang Guo 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1099-1110
The expressions to calculate the critical rate of temperature rise of thermal explosion $ ({\text{d}}T / {\text{d}}t)_{{\text{T}_{\text{b}} }} $ for energetic materials (EMs) were derived from the Semenov’s thermal explosion theory and autocatalytic reaction rate equation of nth order, CnB, Bna, first-order, apparent empiric-order, simple first-order, Au, apparent empiric-order of m = 0, n = 0, p = 1 and m = 0, n = 1, p = 1, using reasonable hypotheses. A method to determine the kinetic parameters in the autocatalytic-decomposing reaction rate equations and the $ ({\text{d}}T / {\text{d}}t)_{{\text{T}_{\text{b}} }} $ in EMs when autocatalytic decomposition converts into thermal explosion from data of DSC curves at different heating rate was presented. Results show that (1) under non-isothermal DSC conditions, the autocatalytic-decomposing reaction of NC (12.97 % N) can be described by the first-order autocatalytic reaction rate equation dα/dt = 1016.00exp(?174520/RT)(1 ? α) + 1016.00exp(?163510/RT)α(1 ? α); (2) the value of $ ({\text{d}}T / {\text{d}}t)_{{\text{T}_{\text{b}} }} $ for NC (12.97 % N) when autocatalytic decomposition converts into thermal explosion is 0.354 K s?1. 相似文献
944.
The evolution of amorphous calcium carbonate (ACC) into crystals in ethanol/water binary solvents under ambient temperature was investigated, and it was found to depend on the volume ratio of ethanol to water (R). Calcite remained dominant when the amount of water was high (R = 1/3). A slight change in the amount of ethanol (R = 3/1) could lead to a dramatic change in the polymorph from calcite to aragonite. However, when poly (allylamine hydrochloride) (PAH) was added at R = 3/1, almost pure vaterite could be obtained, which has a specific morphological variation (from hollow microspheres to cloud‐like). This study provides an alternative polymorphic route for the CaCO3 mineral by using the evolution of ACC in different solvent environments, which provides some useful clues for understanding the importance of kinetic control of the morphologies and polymorphs of a wide range of inorganic materials. In addition, this simple mild phase‐controlled synthetic method could be scaled up as a green chemistry route for the industrial production of different polymorphs of CaCO3. 相似文献
945.
Weizhao Hu Bibo Wang Xin Wang Hua Ge Lei Song Jian Wang Yuan Hu 《Journal of Thermal Analysis and Calorimetry》2014,117(1):27-38
Ethyl cellulose, a widely used bio-degradable shell material, microencapsulated ammonium polyphosphate (MAPP) was added to the bio-degradable poly(butylene succinate) (PBS) to improve its flame retardancy, compatibility, and thermal stability. The MAPP was well characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), water contact angle, and thermogravimetric (TG) analysis. The SEM results indicate the improved dispersion of MAPP into PBS matrix and the formation of the strong interfacial adhesion between MAPP and PBS than APP. With the incorporation of MAPP and char-forming agent into PBS, the limiting oxygen index of the composite was increased to 35.5 %, and the sample can pass the UL-94 V-0 rating, while the un-microencapsulated counterpart cannot reach the rating. The cone calorimeter test showed that the peak heat release rate was decreased by 46.7 % and the burning time was also prolonged compared to the pure PBS. The increased melt flow index and rheology test indicated the increase of viscosity and the improvement of anti-dripping properties. Moreover, the mechanical properties and thermal stability of MAPP composite were also obviously enhanced after the microencapsulation by mechanical, dynamical mechanical thermal analysis, and TG analysis. 相似文献
946.
Zhaolei Li Xiaoming Jiang Huanhuan Gao Dongshan Zhou Wenbing Hu 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1531-1536
We employed fast-scan chip-calorimeter (FSC) measurement (Flash DSC1) to study the melting of syndiotactic polystyrene after melt-crystallized at various cooling rates as well as after isothermally crystallized at various high temperatures. We attributed the observed double melting peak to a melting-recrystallization process of beta-form crystals upon heating, as evidenced by their variations with different cooling and heating rates. Our experiments demonstrated the advantages of FSC techniques in the investigation of crystallization and melting behaviors of polymer materials. 相似文献
947.
Guishan Zou Xiukang Yang Xianyou Wang Long Ge Hongbo Shu Yansong Bai Chun Wu Haipeng Guo Liang Hu Xin Yi Bowei Ju Hai Hu Di Wang Ruizhi Yu 《Journal of Solid State Electrochemistry》2014,18(7):1789-1797
The Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres are firstly prepared and subsequently transferred into the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the Al2O3-coated Li-rich Li1.3[Ni0.35Mn0.65]O2+x sample has a typical α-NaFeO2 layered structure with the existence of Li2MnO3-type integrated component, and the Al2O3 layer is uniformly coated on the surface of the spherical Li-rich Li1.3[Ni0.35Mn0.65]O2+x particles with a thickness of about 4 nm. Importantly, the Al2O3-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% Al2O3-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g?1 at a rate of 0.1 C in the voltage of 2.0–4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% Al2O3-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% Al2O3-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g?1 even at 10 C. Besides, the thin Al2O3 layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li1.3[Ni0.35Mn0.65]O2+x . 相似文献
948.
Chunxiang Hu Yunyun He Shuiliang Chen Yongmei Zhu Muddasir Hanif Haoqing Hou 《Journal of Solid State Electrochemistry》2014,18(10):2797-2802
A binder-free activated carbon paper (ACP) was simply prepared for electric double-layer capacitors by the carbonization of filter paper, followed by heat-air activation at a lower temperature. The electrochemical cells assembled using the as-prepared ACP-470 provides a high specific capacitance of 296.4 F g?1 at current density of 0.5 A g?1 and a high rate performance at a current density of 150 A g?1 with a capacitance of 191.2 F g?1 and a high cycle ability at 10,000 recycles with 100 % capacitance retention. In addition, the ACP has a lower electrical resistivity and provides an effective energy storage performance with a maximum energy density of 41.2 Wh kg?1 and a maximum power density of 138.0 kW kg?1 in a voltage range of 1 V. 相似文献
949.
Jinfa Chang Dr. Ligang Feng Prof. Dr. Changpeng Liu Prof. Dr. Wei Xing Prof. Dr. Xile Hu 《Angewandte Chemie (International ed. in English)》2014,53(1):122-126
The direct formic acid fuel cell is an emerging energy conversion device for which palladium is considered as the state‐of‐the‐art anode catalyst. In this communication, we show that the activity and stability of palladium for formic acid oxidation can be significantly enhanced using nickel phosphide (Ni2P) nanoparticles as a cocatalyst. X‐ray photoelectron spectroscopy (XPS) reveals a strong electronic interaction between Ni2P and Pd. A direct formic acid fuel cell incorporating the best Pd–Ni2P anode catalyst exhibits a power density of 550 mW cm?2, which is 3.5 times of that of an analogous device using a commercial Pd anode catalyst. 相似文献
950.
Following Solid‐Acid‐Catalyzed Reactions by MAS NMR Spectroscopy in Liquid Phase—Zeolite‐Catalyzed Conversion of Cyclohexanol in Water
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Aleksei Vjunov Mary Y. Hu Dr. Ju Feng Dr. Donald M. Camaioni Dr. Donghai Mei Dr. Jian Z. Hu Dr. Chen Zhao Prof. Dr. Johannes A. Lercher 《Angewandte Chemie (International ed. in English)》2014,53(2):479-482
A microautoclave magic angle spinning NMR rotor is developed enabling in situ monitoring of solid–liquid–gas reactions at high temperatures and pressures. It is used in a kinetic and mechanistic study of the reactions of cyclohexanol on zeolite HBEA in 130 °C water. The 13C spectra show that dehydration of 1‐13C‐cyclohexanol occurs with significant migration of the hydroxy group in cyclohexanol and the double bond in cyclohexene with respect to the 13C label. A simplified kinetic model shows the E1‐type elimination fully accounts for the initial rates of 1‐13C‐cyclohexanol disappearance and the appearance of the differently labeled products, thus suggesting that the cyclohexyl cation undergoes a 1,2‐hydride shift competitive with rehydration and deprotonation. Concurrent with the dehydration, trace amounts of dicyclohexyl ether are observed, and in approaching equilibrium, a secondary product, cyclohexyl‐1‐cyclohexene is formed. Compared to phosphoric acid, HBEA is shown to be a more active catalyst exhibiting a dehydration rate that is 100‐fold faster per proton. 相似文献