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SYNTHESIS AND CHARACTERIZATION OF SILAZANE OLIGOMER CONTAINING 1,1,3,3,5,5-HEXAMETHYLCYCLOTRISILAZANE

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Chinese Journal of Polymer science 2000年第5期18卷 449-452页

作者： Cai-hong Xu Ning Zhou Ze-min Xie center for molecular science, Institute of Chemistry, Chinese Academy of sciences, Beijing 100080, China Chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

A new silazane oligomer containing cyclotrisilazane was synthesized by KH-catalyzed dehydro-coupling reactions between diphenylsilane and 1,1,3,3,5,5-hexamethylcyclotrisilazane (D-3(N)).

关键词： silazane oligomer diphenylsilane cyclotrisilazane dehydro-coupling reaction

SOLID PHASE TRANSITION OF SYNDIOTACTIC POLYSTYRENE IN SUPERCRITICAL CO_2

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Chinese Journal of Polymer science 2002年第3期20卷 191-196页

作者： Yu-ying Li Jia-song He State Key Laboratory of Engineering Plastics, center for molecular science, Institute of Chemistry Chinese Academy of sciences, Beijing 100080 China Chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Engn Plast Beijing 100080 Peoples R China

Solid phase transition of the a form crystals to the 3 form crystals in syndiotactic polystyrene (sPS) samples has occurred in supercritical CO2. This transformation is different from those detected under other conditions. The effects of some factors (e.g. time, temperature, and pressure) on the solid phase transformation of sPS in supercritical CO2 were analyzed in detail. Experimental results show that longer time, higher temperature or higher pressure favors the transformation of the a form crystals to the beta form crystals.

关键词： solid phase transition syndiotactic polystyrene supercritical CO2

A Facile Synthesis Route to 1,3-dichlorodisilazanes

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Chinese Chemical Letters 2000年第9期11卷 765-766页

作者： Cai Hong XU Ning ZHOU Ze Min XIE center for molecular science, Institute of Chemistry, the Chinese Academy of sciences, Beijing 100080 Acad Sinica Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

A new 1,3-dichlorodisilazane, 1,3-dichloro-1,3-dimethyl-1,3-divinyldisilazane (DMDV), was prepared from the reaction of hexamethyldisilazane (MMN) and methylvinyldichlorosilane. And use the same method, 1,3-dichloro-1... 详细信息

关键词： Silazanes synthesis dichlorodisilazanes

Synthesis of Macrocyclic Lactones Building on Double Calix[4]arenes

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Chinese Chemical Letters 2000年第10期11卷 403-404页

作者： Qi Yu ZHENG Chuan Feng CHEN Zhi Tang HUANG (center for molecular science, Institute of Chemistry, The Chinese Academy of sciences, Beijing 100080) Chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

The macrocyclic lactones building on calix[4]arenes 3a-b and double calix[4]arenes 4a-b were synthesized by the reaction of p-tert-butylcalix[4]arene (1a) or calix[4]arene (1b) with glycol bis(2-chloroacetate) (2). Th... 详细信息

关键词： macrocyclic lactones double calixarenes synthesis

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VISCOELASTIC BEHAVIOR OF THE NON-HOOKE DEFORMATION BEFORE YIELDING IN UNIAXIAL DRAWING OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)

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Chinese Journal of Polymer science 2001年第4期19卷 399-405页

作者： Zhen-hua Yuan De-yan Shen Ren-yuan Qian Polymer Physics Laboratory center for molecular science, Institute of Chemistry Chinese Academy of sciences, Beijing 100080 China Chinese Acad Sci Inst Chem Ctr Mol Sci Polymer Phys Lab Beijing 100080 Peoples R China

Viscoelastic behavior of the non-Hooke deformation of amorphous PET film before yield was investigated in the temperature region 74-80.5 degreesC around the glass transition temperature. The film specimen was drawn to yield point followed by unloading to zero stress, then the residual deformation was held constant; while the subsequent evolution of the stress was recorded. An induction period was found in the course of stress evolution followed by a stress step-increase. The induction period decreases with increasing drawing temperature with an activation energy of 1.10 MJ/mol.K, which is attributed to the time needed for the relaxation of rubbery deformation through cooperative internal rotations. At temperatures lower than 74 degreesC, there is no stress increase or the induction period becomes too long to be observed. Thus the nature of anelasticity in the non-Hooke region before yielding is attributed to stress induced rubbery deformation. The experimental results are interpreted in terms of Perez' theological model of a series connected Hooks spring and a Voigt element consisting of a parallel connected elastic spring and a dashpot.

关键词： pre-yield deformation PET uniaxial drawing non-Hooke deformation viscoelasticity stress induced rubbery deformation

Key Conditions in Capillary Electrophoresis of Amino Acids with Indirect Ultraviolet Detection

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Chinese Chemical Letters 2000年第9期11卷 803-806页

作者： Zhi Xin WANG Yi CHEN Qing GUO center for molecular science. Institute of Chemistry. The Chincse Academy of sciences. Beijing 100080 Chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

Key factors for capillary electrophoresis of amino acids with indirect ultraviolet detection were illustrated. Buffer compositions and additives were found to be influential as expected, while buffer pH was shown to be particularly critical to the separation and detection. The effect of pH also depended on the electrophoretic mode used. Ways to obtain recurring and selective were suggested.

关键词： amino acids capillary electrophoresis indirect ultraviolet detection

Stereocomplex Formation of Atactic Poly(methyl mcthacrylate)

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Chinese Chemical Letters 2000年第5期11卷 405-406页

作者： Qun GU De Yan SHEN (Polymer Physics Laboratory, center for molecular science, Institute of Chemistry, Chinese Academy of sciences, Bet.jing 100080) Chinese Acad Sci Inst Chem Ctr Mol Sci Polymer Phys Lab Beijing 100080 Peoples R China

Stereocomplexes formed in atactic poly(methyl methacrylatc) (α-PMMA) films cast form different solvents were studied by means of Fourier transform infrared spectroscopy (FTIR). and differential scanning calorimetry (... 详细信息

关键词： Atactic poly(methyl methacrylate) stereocomplex annealing.

Multiple Melting Endotherms of Syndiotactic Polystyrene in β Crystalline Form

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Chinese Chemical Letters 2000年第4期11卷 367-368页

作者： Zhen Hua YUAN De Yan SHEN (Polymer Physics Laboratory, center for molecular science. Institute of Chemistry. Chinese Academy of sciences, Beijing 100080) Chinese Acad Sci Inst Chem Ctr Mol Sci Polymer Phys Lab Beijing 100080 Peoples R China

A series of syndiotactic polystyrene (SPS) samples in β crystalline form were prepared by cooling from the melt at various cooling rates. The effects of cooling rate from the melt, and DSC heating rate on the multiple melting behaviors of β crystals were investigated by differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), from which the *** the multiple melting behavior was ascribed to the occurring of a recrystallization process.

关键词： Multiple melting behavior syndiotactic polystyrene recrystalliation.

A NOVEL TITANIUM COMPLEX WITH LINKED β-DIKETONATO-INDENYL LIGAND FOR CATALYTIC SYNDIOSPECIFIC POLYMERIZATION OF STYRENE

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Chinese Journal of Polymer science 2002年第3期20卷 213-217页

作者： Jun Wang De-min Xu Zhong-yang Liu Yong-jun Chen Dong Wang center for molecular science, Institute of Chemistry Chinese Academy of sciences, Beijing 100080, China Chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

A novel ligand (3), in which the indenyl group is linked to a β-diketone moiety through a three-carbon bridge, andits titanium complex (4) were synthesized. The titanium complex was employed as a metallocene analog with co-catalystmethylaluminoxane (MAO) in catalytic syndiospecific polymerization of styrene to give highly syndiotactic polystyrene(s-PS, 96%-97%). Polymerization temperature (T_p) strongly influenced the catalytic activity and syndiotacticity of theproduced PS. The activities of catalyst 4 increase from 1.84×10~6 to 3.26×10~6 gPS/molTi·h with the increase of T_p from60℃ to 80℃ and the syndiotacticities of the produced s-PS also increase slightly. Then, both the catalytic activity and thesyndiotacticity of PS decrease at T_p of 90℃.

关键词： β-Diketone Metallocene Syndiospecific polymerization Polystyrene