Carbon Papers from Tall Goldenrod Cellulose Fibers and Carbon Nanotubes for Application as Electromagnetic Interference Shielding Materials

To transform tall goldenrods, which are invasive alien plant that destroy the ecosystem of South Korea, into useful materials, cellulose fibers isolated from tall goldenrods are applied as EMI shielding materials in this study. The obtained cellulose fibers were blended with CNTs, which were used as additives, to improve the electrical conductivity. TGCF/CNT papers prepared using a facile paper manufacturing process with various weight percent ratios and thickness were carbonized at high temperatures and investigated as EMI shielding materials. The increase in the carbonization temperature, thickness, and CNT content enhanced the electrical conductivity and EMI SE of TGCF/CNT carbon papers. TGCF/CNT-15 papers, with approximately 4.5 mm of thickness, carbonized at 1300 °C exhibited the highest electrical conductivity of 6.35 S cm⁻¹, indicating an EMI SE of approximately 62 dB at 1.6 GHz of the low frequency band. Additionally, the obtained TGCF/CNT carbon papers were flexible and could be bent and wound without breaking.     

Curing characteristics of o-cresol novolac epoxy resin modified by bismaleimide

Curing characteristics of o-cresol novolac epoxy resin modified by 4,4-diaminodiphenylmethane bismaleimide (DDM-BMI) using FTIR were investigated and the glass transition temperature was measured. With the addition of DDM as hardener, the relative curing reaction conversion of DDM-BMI increased with equivalent weight ratio [R₁ = (equiv wt summation of epoxy and DDM-BMI)/equiv wt of DDM] and weight ratio of epoxy and DDM-BMI (R₂ = wt of epoxy resin/wt of DDM-BMI). Using phenol novolac resin (PN) as hardener, the curing reaction conversion of DDM-BMI was hardly changed, but the variation of that in the epoxy resin was observed with R₂ change. © 1996 John Wiley & Sons, Inc.     

金属活动性顺序的认识误区

我们通常所用的金属活动性顺序是指标准状态下金属在水溶液中活动性相对大小的顺序。它是按水溶液中金属单质与其对应离子所组成电极的标准电极电位由小到大的顺序排列而成的。     

Mathematical modeling of prolonged cycling of a porous cadmium electrode in alkaline power sources

An analysis of a computer model of a porous cadmium electrode is presented. The model describes prolonged cycling of the electrode under the alkaline battery conditions. It allows the evaluation of the dependence of the cathodic and anodic polarization on the concentration of the alkaline electrolyte, the charge and discharge current density, and the thickness and porosity of the electrode. The effect of the mass transfer of the active substance along the electrode thickness on the electrode capacity during the battery cycling can also be predicted. The calculations took into account that the cathodic and anodic processes on the cadmium electrode occurred by the liquid- and solid-state mechanisms. The diffusion, migration, and convective transport of the electrolyte components were also taken into account. An analysis of data using this model showed that it can be used in studies of the capacity of sintered cadmium electrodes under different operating conditions of nickel-cadmium batteries.     

Growth behavior of Bi2Te3 and Sb2Te3 thin films on graphene substrate grown by plasma‐enhanced chemical vapor deposition

A comparative study of the substrate effect on the growth mechanism of chalcogenide Bi₂Te₃ and Sb₂Te₃ thin films was carried out. Obvious microstructural discrepancy in both the as‐deposited Bi₂Te₃ and Sb₂Te₃ thin films was observed when grown on graphene or SiO₂/Si substrate. Bi₂Te₃ and Sb₂Te₃ thin films deposited on the graphene substrate were observed to be grown epitaxially along c‐axis and show very smooth surface compared to that on SiO₂/Si substrate. Based on the experimental results of this study, the initial adsorption sites on graphene substrate during deposition process, which had been discussed theoretically, could be demonstrated empirically.     

Transfer hydrogenation of ketones to alkanes using tributylamine under heterogeneous Pd/C catalysis

Ketones undergo transfer hydrogenation using tributylamine in dioxane in the presence of a catalytic amount of Pd/C to give the corresponding alkanes. Copyright © 2014 John Wiley & Sons, Ltd.     

Star‐shaped polymers having side chain poss groups for solid polymer electrolytes; synthesis,thermal behavior,dimensional stability,and ionic conductivity

A series of organic/inorganic hybrid star‐shaped polymers were synthesized by atom transfer radical polymerization using 3‐(3,5,7,9,11,13,15‐heptacyclohexyl‐pentacyclo[9.5.1.1^3,9.1^5,15.1^7,13]‐octasiloxane‐1‐yl)propyl methacrylate (MA‐POSS) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) as monomers and octakis(2‐bromo‐2‐methylpropionoxypropyldimethylsiloxy)octasilsesquioxane as an initiator. Star‐shaped polymers with methyl methacrylate (MMA) and PEGMA moieties were also prepared for comparison purposes. Dimensionally stable freestanding film could be obtained from the hybrid star‐shaped polymer containing 26 wt % of MA‐POSS moieties although its glass transition temperature is very low, ?60.9 °C. As a result, the hybrid star‐shaped polymer electrolyte containing lithium bis(trifluoromethanesulfonyl)imide showed ionic conductivities (1.75 × 10^?5 S/cm at 30 °C), which were two orders of magnitude higher than those of the star‐shaped polymer electrolyte with MMA moieties. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012