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RHEOLOGICAL BEHAVIOR OF EPOXY RESIN WATERBORNE DISPERSIONS

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Chinese Journal of polymer Science 2001年第5期19卷 471-476页

作者： Zhen-zhong Yang Yuan-ze Xu de-lu {2. State Key {3. of polymer {2. & {3., Center for Molecular Science institute of chemistry, Chinese Academy of Sciences, Beijing 100080 china 中科院化学所高分子物理与化学国家重点实验室北京

The waterborne dispersions of epoxy resin were prepared by the phase inversion emulsification technique. Rheological behavior and its relationship with the structural change of the systems were studied. It was shown that the concentrated dispersions were highly viscoelastic and pseudoplastic, which was attributed to the formation of a physical network among the waterborne particles via hydrogen bond. The dilute dispersions were Newtonian fluids. The discrete clusters composed of small waterborne particles were found in diluted dispersions. With increasing solid content, there existed a structural transition via percolation through a cluster-cluster aggregation mode to form the physical network, which was qualitatively evidenced by the TEM morphologies.

关键词： epoxy resin waterborne dispersion rheological behavior cluster-cluster aggregation percolation transition

TRANSIENT EFFECT OF A BOGER FluID FLOWING AROUND A CONFINED CYLINdeR

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Chinese Journal of polymer Science 2001年第4期19卷 377-384页

作者： Xian-feng Li Huai-tian Bu de-lu {2. State Key {3. of polymer {2. and {3. Center for Molecular Science,institute of {3., Chinese Academy of Sciences, Beijing 100080, china 中科院化学所高分子物理与化学国家重点实验室北京

This paper is concerned with the numerical simulation of the transient effect of an inertialess Boger flow past a confined circular cylinder and the comparison of predictions with particle image velocimetry (PIV) measurements given by Shiang et al.. Dynamic simulation based on the Oldroyd-B constitutive model was carried out using a Lagrangian-Eulerian algorithm. The evo{2.tion of velocity field was obtained for the flow at two deborah (de) numbers, i.e. de = 1.2.and 3.0. At low de, the flow reached steady state rapidly, and showed a symmetric flow regime. However, at high de, the time required to reach steady flow behind the cylinder increased significantly, and the distribution of the velocity field appears to be asymmetric with respect to the stagnation line. Fairly good agreement between the numerical results and the experimental observations is reported. It can be conc{2.ded that both the experimental measurements and the present simulations indicate that the elasticity of the polymeric flow strongly affect the flow regime of viscoelastic flow around a confined cylinder.

关键词： transient effect flow around a cylinder Lagrangian-Eulerian algorithm Oldroyd-B model

λ/2.-Thick cavity for mimicking electromagnetically induced transparency at telecommunication wavelengths

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Advanced Photonics 2024年第3期6卷 42-50页

作者： Hua lu Shouhao Shi Dikun Li Shuwen Bo Jianxu zhao Dong Mao Jianlin zhao Northwestern Polytechnical University School of Physical Science and TechnologyMOE Key Laboratory of Material Physics and Chemistry under Extraordinary ConditionsKey Laboratory of Light-Field Manipulation and Information AcquisitionMinistry of Industry and Information TechnologyShaanxi Key Laboratory of Optical Information TechnologyXi’anChina

Optical cavities play crucial roles in enhanced light-matter interaction,light control,and optical communications,but their dimensions are limited by the material property and operating *** planar cavities are urgently in demand for large-area and integrated optical ***,extremely reducing the planar cavity dimension is a critical challenge,especially at telecommunication ***,we demonstrate a type of ultrathin cavities based on large-area grown Bi_(2.Te_(3.topological insulator(TI)nanofilms,which present distinct optical resonance in the near-infrared *** result shows that the Bi_(2.Te_(3.TI material presents ultrahigh refractive indices of>6 at telecommunication *** cavity thickness can approach 1/2. of the resonance wavelength,superior to those of planar cavities based on conventional Si and Ge high refractive index ***,we observed an analog of the electromagnetically induced transparency(EIT)effect at telecommunication wavelengths by depositing the cavity on a photonic *** EIT-like behavior is derived from the destructive interference coupling between the nanocavity resonance and Tamm *** spectral response depends on the nanocavity thickness,whose adjustment enables the generation of obvious Fano *** experiments agree well with the *** work will open a new door for ultrathin cavities and applications of TI materials in light control and devices.

关键词： topological insulator optical nanocavity photonic crystal electromagnetically induced transparency-like effect

Study on the two and three-parameter working stability regions of 3.-TZP suspension

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Science china(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2. ZHANG Xinni3. CHEN Sha’ou3.& QI Ping3.1. department of chemistry, Qingdao University, Qingdao 2.6071,{2. 2. department of chemistry, Tsinghua University, Beijing 100084,{2. 3. department of physics, Qingdao University, Qingdao 2.6071,{2. department of chemistry Qingdao University Qingdao China department of chemistry Tsinghua University Beijing China department of physics Qingdao University Qingdao China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3.-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very di{2.te suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the inf{2.ence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3.-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3.-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3.-TZP, suspension, stability, DLVO theory, interparticle potential energy.

polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

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Chinese Chemical Letters 1997年第8期8卷 725-728页

作者： Zhen Zhong YANG de lu {2. Mao XU({3. physics {2., institute of chemistry, The Chinese Academy of Sciences, Beijing 100080) polymer physics{2. Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

The catalyst boron trifluoride etherate was used to catalyze the reaction of epoxy resin with polyethylene glycol (PEG), and the effect of the concentration of the catalyst on the reaction is studied. It is shown that there exist two competitive reactions : I, self {2.ization of epoxy resin via chain growth and II, co{2.ization of epoxy resin with PEG via step growth. At high concentration of the catalyst reaction I dominates and reaction II is negligible. On the contrary, at low concentration of the catalyst, reaction II dominates and block co{2.s are formed In the intermediate case, the two reactions are comparable with the result that a gel structure is obtained.

关键词： PEG polymerization of Bisphenol A Epoxy Resin with Polyethylene glycol

Interfacial behaviors of PMMA-PEO block copolymers at the air/water interface

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Science china chemistry 2005年第6期48卷 567-573页

作者： CHENG Caixia1, JIAO Tifeng2. TANG Rupei1, LIU Minghua2.& XI Fu1 1. State Key laboratory of {3.{2. and {3., Joint laboratory of {3. Science and Materials, institute of chemistry, Chinese Academy of Sciences, Beijing 100080, china 2. CAS Key laboratory of Colloid and Interface Science, institute of chemistry, Chinese Academy of Sciences, Beijing 100080, china State Key laboratory of polymer{2. and{3. Joint Laboratory of Polymer Science and Materials Institute of Chemistry Chinese Academy of Sciences Beijing China CAS Key laboratory of Colloid and Interface Science Institute of Chemistry Chinese Academy of Sciences Beijing China

Diblock copolymer of PMMA2.1-b-PEO114 and triblock copolymer of PMMA12.-b- PEO2.7-b-PMMA12. were synthesized and their interfacial properties at the air-water interface were investigated, where both blocks of polyethylene oxi{2. (PEO) and poly(methyl methacrylate) (PMMA) are surface active but the former is soluble in water while the latter is not. Both the block copolymers could form monolayers with two obvious transition regions. The first transition point is around 10 mN/m, which could be assigned to the pancake-brush change of the PEO chains. The other is around 18 mN/m, which could be ascribed to the con{2.nsed packing of PMMA. The surface morphological changes during the compression of the Langmuir monolayers are inves-tigated by using the AFM and SEM methods for the films {2.posited at different surface pressure or molecular areas. At a lower surface pressure, a typical morphology of PEO-con- taining lipopolymers is observed. Upon compression, sphere-dominant morphologies were observed. While the diblock copolymer is easy to folding, the triblock copolymer is in favor of formation of circular domains through vesiculation.

关键词： PMMA-PEO, block copolymers, monolayer, Langmuir-Blodgett films, AFM.

Synthesis and Crystal Structure of [Cis-1,10phenanthroline-palladium(Ⅱ)(THF)_2.dinitrate (THF = Tetrahydrofuran)

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Chinese Journal of Structural chemistry 2003年第5期22卷 547-549页

作者： HUANG Hui YU Shu-Yan② (State Key laboratory of polymer{2. and{3., Joint laboratory of polymer Science and Materials, institute of chemistry, The Chinese Academy of Sciences, Beijing 100080, china) institute of chemistry The Chinese Academy of Sciences State Key Laborator6y of Polymer Physics and Chemistry Joint Laboratory of Polymer Science and Materials CAS 北京 100080

A mononuclear complex, cis-1,10-phenanthroline-palladium(Ⅱ)(THF)2.dinitrate (THF = tetrahydrofuran) [Pd(C10H8N2.(C4H8O)2.(NO3.2.1, has been prepared and structurally characterized by single-crystal X-ray diffraction. The crystal belongs to monoclinic system, space group P2./c with a = 7.881(1), b = 2..3.1(3., c = 10.178(1) ? ?= 103.3.3.3.? V = 2.3..5(4) 3. Mr = 554.83. Dc = 1.72. g/cm3. Z = 4, F(000) = 112. and (MoK) = 0.92. mm-1. The structure was refined to R = 0.0678 and wR = 0.1651 for 1687 observed reflections with I > 2.I). It is revealed that the central Pd(Ⅱ) ion in the title complex is bonded to two THF and two phenanthroline molecules in a cis-configuration to form the coordination geometry, deviating slightly from the square plane.

关键词： crystal structure Pd(Ⅱ) complex 1,10-phenanthroline

THERMALLY STIMULATED SHAPE MEMORY BEHAVIOR OF polymerS WITH PHYSICAL CROSSLINKS

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Chinese Journal of polymer Science 1999年第3期17卷 203-213页

作者： Mao Xu Feng-kui Li polymer physics{2.,{3., Chinese Academy of Sciences, Beijing 100080, china 中科院化学所高分子物理及化学国家重点实验室北京 100080 中科院化学所高分子物理及化学国家重点实验室北京

The shape memory effect of polymers was investigated for the purpose of improving the processing conditions of their preparation and broadening the list of polymers for shape memory applications. Emphasis was put on the possibility of using polymers with physical crosslinks as shape memory materials and their structure-function relationships. Segmented block polyurethanes and polyethylene/nylon 6 graft copolymers were used as examples of polymers with physical crosslinks. It was found that these copolymers can really be used as thermally stimulated shape memory materials with large recoverable strain and high final recovery rate. The main advantage of using copolymers is their improved processing conditions as compared with polymers with chemical crosslinks. As only physical crosslinks are introduced, all conventional processing techniques for thermal plastics can be used, and the materials become easily reusable. The results indicate that the high crystallinity of these copolymers at room temperature and the formation of stable physical crosslinks are the two prerequisites for these polymers to exhibit shape memory effect. The successful use of block and graft copolymers imply the possibility of using polymers of various structure and properties as shape memory materials.

关键词： shape memory effect segmented polyurethanes polyethylene nylon graft copolymers

COALESCENCE INDUCED GRADIENT MORPHOLOGY NEAR A WALL IN PHASE SEPARATED polymer BLENDS DURING QUIESCENT ANNEALING

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Chinese Journal of polymer Science 2002年第6期20卷 543-550页

作者： Wei Yu Chi-xing Zhou de-lu {2. department of polymer Science and Engineering, Shanghai Jiao Tong University, Shanghai 2.02.0 china State Key {2. of polymer physics and chemistry, institute of chemistry, Chinese Academy of Sciences Beijing 100080, china department of polymer Science and Engineering Shanghai Jiao Tong University 上海 200240 institute of chemistry Chinese Academy of Sciences State Key Laboratory of Polymer Physics and Chemistry 北京 100080

A fast coalescence mechanism is proposed to account for the wall effect on the formation of gradient morphology in phase separated polymer blends during quiescent annealing. The existence of solid wall with high polarity is believed to change the potential field around the dispersed particles near the wall. This additional potential interaction between the solid wall and the dispersed particles causes faster coalescence of the dispersed particles near the wall than in the bulk. The gradient phase morphology thus formed can be predicted by combining the wall-particle interaction and the touch-coalescence mechanism. The effect of interfacial tension on the gradient morphology is also discussed.

关键词： gradient morphology wall effect coalescence polymer blends interfacial tension