检索结果-南通市图书馆

Effects of water phase concentration on the emulsion polymerization of polyaniline

在线全文

学校读者我要写书评

暂无评论

Journal of central south university of Technology 2001年第2期8卷 140-142页

作者： PAN Chun yue 1,CHEN Zhen hua 2,HUANG Yong li 1,HUANG Ke long 1 (1.College of chemistry and chemical engineering, central south university, changsha 410083, china 2.Department of Materials Science and engineering, central south university, Cha 1. College of chemistry and chemical engineering Central South University 410083 Changsha China 2. Department of Materials Science and engineering Central South University 410083 Changsha China

The emulsion polymerization of aniline in three phase system of xylene functionalized protonic acid water was carried out using (NH 4) 2S 2O 4 as oxidant. The influences of water phase concentration on the viscosity, conductivity, transmittance of polyaniline(PAN) latex and its powders were studied. The results show that the properties of PAN prepared through the emulsion polymerization are influenced by the amount of water used in the polymerization. The morphology of PAN varies with the water phase concentration used in the polymerization, which may result in the change of properties of PAN latex and its powders. When the volume fraction of water (φ) is about 20% 30%, the prepared PAN powder has higher conductivity, and the PAN latex has appropriate viscosity and particle size. The consumption of xylene was reduced at high φ value.

关键词： polyaniline emulsion polymerization water concentration property

Facile synthesis of La_2Mo_2O_9 nanoparticles via an EDTA complexing approach

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2008年第4期27卷 340-344页

作者： CHENG Hua WANG Hongen LI Liang LU Zhouguang QIAN Dong College of chemistry and chemical engineering Central South University Changsha 410083 China State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

A facile EDTA （ethylene diamine tetraacetic acid） complexing technique has been successfully employed to prepare La2Mo2O9 nanoparticles. The as-synthesized products are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and Fourier transform infrared spectroscopy （FT-IR）. The results show that a homogeneous transparent gel can be obtained with EDTA as the organic complexing reagent under the pH value of 3.0. Further thermal decomposition of the as-synthesized transparent gel by increasing the temperature up to 600℃ for 3 h results in the formation of La2Mo2O9 nanoparticles with a crystal size of about 30 nm. Moreover, the nanoparticles tend to form micrometer-sized aggregates with a three-dimensional network structure, which shows promising applications in solid oxide fuel cells （SOFC）, catalysts and so on.

关键词： inorganic non-metal materials EDTA complexing sol-gel La2Mo2O9 nanoparticles porous structure

ISOTHERMAL KINETICS OF THE FIRST STAGE REDUCTION OF MAGNETITE COLD BOND PELLETS WITH CARBON MONOXIDE

在线全文

学校读者我要写书评

暂无评论

Journal of central south university 1998年第1期10卷 2-4页

作者： Chen Qiyuan Zhou Hong Zhang Pingmin(Department of chemistry, central south university of Technology, changsha 410083, china)Qiu Guanzhou Xu Jing(Department of Mineral engineering, central south university of Technology) Department of chemistry Central South University of Technology Changsha 410083 China Department of Mineral engineering Central South University of Technology China

The reduction of Fe3O4 to Fe is accomplished in two stages. In order to understand the reduction mechanism of magnetite cold bond pellets during the first period of heatingup process, it is necessary to study the kinetics of the reaction. In this work, the first stage of reduction of magnetite cold bond pellets, that is the reduction from Fe3O4 to FeO, has been investigated using an isothermal thermogravimetric method. Isothermal experiments were carried out at 750℃, 800℃, 850℃ and 900℃, respectively. The results showed that the reaction was controlled by chemical reaction below 800℃, whereas, at higher temperature, it was controlled by a mixed controlled mechanism of chemical reaction and GinstlingBrounshtein diffusion as well.

关键词： kinetics thermogravimetry reduction cold bond pellet

Synthesis and properties of nickel borate acylate as a new rubber-steel cord adhesion promoter

在线全文

学校读者我要写书评

暂无评论

Journal of central south university of Technology 2001年第4期8卷 244-248页

作者： LI Xiao ru 1,NIE Xi du 2,WU Hai ying 1,CHENG Ben cheng 1 (1 College of chemistry and chemical engineering, central south university, changsha 410083, china 2 Hengyang Branch of Hunan university, Hengyang 412000, china) 1. College of chemistry and chemical engineering Central South University 410083 Changsha China 2. Hengyang Branch of Hunan university 412000 Hengyang China

The synthetic method of nickel borate acylate (NBA), a kind of rubber steel cord adhesion promoter (AP), through nickel carbonate, borate and mixed carboxylic acid was studied. The preparation of nickel carbonate could be performed through reaction of nickel sulfate with sodium carbonate in aqueous solution, in which fractional conversion of nickel was more than 99.9%. The mixed nickel carboxylate was prepared by the reaction of nickel carbonate with isooctanoic acid and acetic acid, under strong stirring for 2 h, the mole ratio of these chemicals were 1∶1∶1.1 respectively, and water should be removed completely by adding of inert organic solvent after reaction was finished so as to avoid hydrolysis of tributyl borate in the second reaction. NBA was synthesized by reaction of mixed nickel carboxylate with tributyl borate under strong stirring at 200 250 ℃ for 6 h. By detection and comparison with 680C product from Manobond Company of England, the NBA synthesized through isooctanoic acid and tributyl borate was very similar to product 680C in IR data, 300% fixed extension strength, tensile strength, hardness and cure curve, and was slightly lower than those of product 680C in tensile failure extensibility and hot air aging. The experimental results show that the prepared NBA can be used as rubber steel cord AP.

关键词： nickel borate acylate adhesion promoter nickel carbonate borate

Influences of Ti substitution on the structure and electrochemical properties of Mg_(1-x)Ti_xNi(x=0,0.1, 0.2, and 0.3) hydrogen storage alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2009年第5期28卷 504-510页

作者： HUANG Hongxia HUANG Kelong LIU Suqin CHEN Dongyang College of chemistry and chemical engineering Central South University Changsha 410083 China Department of Materials and chemical engineering Guilin University of Technology Guilin 541004 China

MgNi-based hydrogen storage alloys Mg1–xTixNi （x = 0, 0.1, 0.2, and 0.3） were prepared by means of mechanical alloying. Mg in the alloy was partially substituted by Ti to improve the cycle stability of the alloys. The effects of the substitution of Ti for Mg on the microstructure and electrochemical performances of the alloys were investigated in detail. The results indicate that the substitution of Ti for Mg obviously decreases the discharge capacity, but it significantly improves their cycle stabilities. The microstructure of the alloys analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM） shows that the alloys have a dominatingly amorphous structure. The substitution of Ti for Mg helps to improve the anti-oxidation/corrosion ability of the MgNi alloy but demolishes the electrochemical kinetics of hydrogenation/dehydrogenation. The Mg0.9Ti0.1Ni alloy electrode milled for 80 h exhibits the best integrative capability, which has the maximal discharge capacity of 331.66 mAh/g and the C30/Cmax of 63.65%.

关键词： hydrogen storage alloys Ti substitution structural characteristic electrochemical properties

chemical synthesis of nanocrystalline ZrO_2-SnO_2 composite powders

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2004年第2期23卷 182-184页

作者： YANG Huaming ZHANG Xiangchao YANG Wuguo HUANG Chenghuan QIU Guanzhou Department of Inorganic Materials, school of Resources Processing and Bioengineering, central south university, changsha 410083, china Department of Inorganic Materials School of Resources Processing and Bioengineering Central South University Changsha 410083

ZrO_2-SnO_2 composite nanoparticles were prepared by heating the hydrateprecursors synthesized by the chemical co-precipitation reaction of ZrOCl_2 and SnCl_4. Theprecursors were examined by differential thermal analysis (DTA) and thermogravimetric analysis(TGA). The composite powder was characterized using X-ray diffraction (XRD), transmission electronmicroscopy (TEM) and desorption isotherm (Barrett-Joyner-Halenda method). The average crystal sizeof the nanoparticle ranges from 15 to 30 nm for the sample containing 5%-25% ZrO_2 (mass fraction).Most of the pores in the ZrO_2-SnO_2 nanoparticles are about 10-20 nm in diameter. The compositepowder is promising for chemical sensors.

关键词： inorganic materials ZrO_2-SnO_2 nanocomposites chemical synthesis doping pore structure

Enhancement in Activity of a Vanadium Catalyst for the Oxidation of Sulfur Dioxide by Radio Frequency Plasma During the Preparation Process

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas chemistry 2003年第3期12卷 195-200页

作者： Zhenxing Chen, Honggui Li, Lingsen WangState Key Laboratory for Powder Metallurgy, College of chemistry and chemical engineering, central south university, changsha 410083, china State Key Laboratory for Powder Metallurgy College of Chemistry and Chemical Engineering Central South University

Radio frequency plasma was used to prepare a vanadium catalyst. The resultsshowed that activating time of the catalyst could be shortened quickly and the catalytic activitywas improved to some extent with the use of plasma. Catalyst Ls-9 was prepared under an optimalcondition of 40 W discharge power, 10 min discharge time and 8 Pa gas pressure. The catalyticactivity was up to 54.7% at 410℃, which was 2.2% higher than that of the Ls-8 catalyst. Only 10 minwas needed to activate the catalyst with plasma, which was 1/9 of the traditional calcination *** Ls-9, both the endothermic as well as the exothermic peaks detected by differential thermalanalysis shifted to higher temperatures obviously, indicating that its crystal phase could melteasily. There existed an apparent endothermic peak at 283℃. SEM photographs showed a uniform sizedistribution. It is inferred that the quadrivalent vanadium compound may exist mainly in the form ofVOSO_4.

关键词： plasma activation dispersion vanadium catalyst low-temperature activity

Activity Enhancement of Vanadium Catalysts with Ultrasonic Preparation Process for the Oxidation of Sulfur Dioxide

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas chemistry 2003年第2期12卷 139-144页

The effect of ultrasonic cavitations on the activity of vanadium catalysts atlow temperatures for the oxidation of sulfur dioxide, in which refined carbonized mother liquor hadbeen added, was investigated. Twenty minutes were needed to produce obvious cavitations when thecatalyst raw material was treated in the 50 W ultrasonic generator. However, only 10 minutes wouldbe needed in a 150 W ultrasonic generator. The higher the temperature of the wet material, the lesstime was needed to produce cavitations, and the optimal temperature was 60℃. The water content inthe wet material mainly affected the quantity of cavitations. Ls-8 catalyst was prepared usingultrasonic. Its activity for conversion of SO_2 reached to 52.5% at 410℃ and 4.2% at 350℃. Thedifferential thermal analyses indicate that both endothermic peaks and exothermic peaks noticeablyshifted forward compared with Ls catalyst prepared without ultrasonic, and SEM results show auniform pore size distribution for Ls-8 catalyst.

关键词： ultrasonic dispersion vanadium catalyst low temperature activity sulfurdioxide cavitation

Study on Syntheses and Characterizations of Polymethylphenethylsilane, Polymethylcyclohexylsilane and their Copolymers

在线全文

学校读者我要写书评

暂无评论

Journal of central south university 2000年第2期12卷 92-96页

作者： HU Hui ping 1,HUANG Ke long 1,PAN Chun yue 1,CHEN De ben 2 (1 College of chemistry and chemical engineering, central south university of Technology, changsha 410083, china 2 Department of chemistry, Sichuan university, Chengdu 610064, china 1. College of chemistry and chemical engineering Central South University of Technology 410083 Changsha China 2. Department of chemistry Sichuan University 610064 Chengdu China

The effects of adding cosolvents of diglyme and 15-crown-5 to the reaction mixture of Wurtz-type coupling of dichlorosilanes on the yield and relative molecular mass dispersity of polymethylphenethylsilane(PMPES) were discussed. The results show that addition of 10%(volume ratio of diglyme to toluene) diglyme as a cosolvent to the reaction mixture leads to the yield increase of PMPES with a monomodal distribution of relative molecular masses. Adding 10%diglyme to the reaction mixtures, the yields of polymethylcyclohexylsilane(PMCS) and copolymers (polymethylphenethylsilane-co-methylcyclohexylsilane), (the molar ratios of methylphenethyldichlorosilane to methylcyclohexyldichlorosilane were 2.0, 1.0 and 0.5, and the copolymers were abbreviated by Copolymers I, II, III, respectively) are 47%, 52%, 54%, 53%, respectively. Their relative molecular masses ([`(M)]w )(\bar M_w ) almost reach 105. These polysilanes were characterized by 1H-NMR, IR and UV absorption spectrum.

关键词： polysilane cosolvent synthesis characterization