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BRITTLE-DUCTILE TRANSITION OF POLYMERS AND ITS PERCOLATION MODEL

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Chinese Journal of Polymer Science 2003年第2期21卷 129-134页

作者： Wei Jiang Li-jia An Bing-zheng Jiang State Key Laboratory of Polymer physics and chemistry Changchun institute of Applied chemistry Chinese Academy of Sciences, Changchun 130022, China Chinese Acad Sci Changchun Inst Appl Chem State Key Lab Polymer Phys & Chem Changchun 130022 Peoples R China

The brittle-ductile transition (BDT) of particlc toughened polymers was extensively studied in terms ofmorphology, strain rate, and temperature. The calculation results showed that both the critical interparticle distance (ID_c) andthe brittle-ductile transition temperature (T_(BD)) of polymers were a function of strain rate. The ID_c reduced nonlinearly withincreasing strain rate, whereas T_(BD) increased considerably with increasing strain rate. The effects of temperature andplasticizer concentration on BDT were discussed using a percolation model. The results were in agreement with theexperiments.

关键词： Particle toughening polymers Brittle-ductile transition Percolation

Microstructure Characterization of Short-chain Branching Polyethylene with Differential Scanning Calorimetry and Successive Self-nucleation/Annealing Thermal Fractionation

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Chinese Journal of Polymer Science 2014年第6期32卷 751-757页

作者： Yan-hu Xue Yan-hui Wang Yan-di Fan He-ran YangState Key Laboratory of Polymer physics and chemistry Changchun institute of Applied chemistry Chinese Academy of Sciences Tao Tang Shu-qin Bo 姬相玲 State Key Laboratory of Polymer physics and chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

A series of the copolymers of ethylene with 1-hexene （M1-M9） synthesized by metallocene catalyst Et[Ind]2ZrC1JMAO was studied by differential scanning calorimetry and successive self-nucleation and annealing （SSA） thermal fractionation. The distribution of methylene sequence length （MSL） in the different copolymers was determined using the SSA method. The comonomer contents of samples M4 and M5 are 2.04 mol% and 2.78 mol%, respectively. Both M4 and M5 have low comonomer content and their MSL distribution profiles exhibit a monotonous increase trend with their MSL. The longest MSL of M5 is 167, and its corresponding molar percent is 43.95%, which is higher than that of M4. Moreover, the melting temperature （Tm） of M5 is also higher than that of M4. The comonomer contents of samples M7, M8, and M9 are 8.73 mol%, 14.18 mol% and 15.05 mol%, respectively. M7, M8, and M9 have high comonomer contents, and their MSL distribution profiles display unimodality. M7 has a lower peak value of 33 and a narrow MSL distribution, resulting in a Tm lower than that of M8 and M9. The MSL and its distribution are also key points that influence the melting behavior of copolymers. Sometimes, MSL and its distribution of copolymers have a greater impact on it than the total comonomer contents, which is different from traditional views.

关键词： Polyethylene Methylene sequence length (MSL) Microstructure Successive self-nucleation and annealing(SSA) SCB.

MOLECULAR SIMULATION STUDY ON THE CHANGE OF POLYMER STRUCTURE DURING YIELDING

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Chinese Journal of Polymer Science 2001年第5期19卷 527-529页

作者： Chen-guang Xu Tai-ning Liang Juan Sun Xiao-zhen Yang State Key Laboratory of Polymer physics and chemistry 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 Polymer Phys & Chem Beijing 100080 Peoples R China

A better understanding of a recently raised argument on whether there occurs a structure change during yielding has been acquired by using molecular simulation. That is, when monitoring the displacements of all atoms before and after the yield, a structure transition does occur, which is the 'atomic jump' that coordinates the amount of the atoms in the polymer and makes a large step beyond similar to0.05 nm for all those atoms. Results indicate that the complex of polymer chain packing induces the multiple atomic jumps around the yield point. This explains why polymers have a broader yielding peak.

关键词： polymer deformation yield structure transition atomic jump multiple yields

Local electronic structure and magnetic properties of 3d transition metal doped GaAs

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Science China(physics,Mechanics & Astronomy) 2008年第5期51卷 470-480页

作者： LIN He1 & DUAN HaiMing21 Department of chemistry,institute of Applied chemistry,Xinjiang University,Urumqi 830046,China 2Department of physics,Xinjiang University,Urumqi 830046,China 1. Department of chemistry Institute of Applied Chemistry Xinjiang University Urumqi 830046 China 2. Department of physics Xinjiang University Urumqi 830046 China

The local electronic structure and magnetic properties of GaAs doped with 3d transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni) were studied by using discrete variational method (DVM) based on density functional theory. The calculated result indicated that the magnetic moment of transition metal increases first and then decreases, and reaches the maximum value when Mn is doped into GaAs. In the case of Mn concentration of 1.4%, the magnetic moment of Mn is in good agreement with the experimental result. The coupling between impure atoms in the system with two impure atoms was found to have obvious variation. For different transition metal, the coupling between the impure atom and the nearest neighbor As also has different variation.

关键词： diluted magnetic semiconductor density functional theory 3d transition metal cluster model electronic structure

Molecular Mechanics Study on Asymmetry Catalysis

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Chinese Chemical Letters 1999年第9期10卷 751-754页

作者： Da Wei GUO Xiao Zhen YANG(Polymer physics Laborator. institute of chemistry. Chinese Academy of Sciences.Beijing, 100080) Chinese Acad Sci Inst Chem Polymer Phys Lab Beijing 100080 Peoples R China

A ground state model about an asymmetry hydrogenation of methyl pyruvate over Pt-nanocluster catalyst with a modifier cinconidine has been built. The role of the modifier in the catalytic process is explained.

关键词： molecular mechanics asymmetry catalysis methyl pyruvate Pt-cluster catalyst modifier

An Effectual Way to Construct Phase Diagrams

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工程科学学报 1991年第2期 154-161页

作者： Qiao Zhiyu Liang fingkui Rao Guanghui (Department of Physical chemistry) institute of physics, Academia Sinica, Beijing Academia Sinica Beijing institute of physics

It is described that the effectual way to construct phase diagrams is the combination of computer calculation with some critical measurements. Examples of application to the CuO-RE2O3 (RE. La, Y, Nd), Na2 B2O4, K2B2O4... 详细信息

关键词： phase diagram computer calculation DTA

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

A MULTIGRID METHOD FOR NONLINEAR PARABOLIC PROBLEMS

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Journal of Computational Mathematics 1996年第4期14卷 363-382页

作者： x.J. Yu(Laborutory of Computational physics, institute of Applied physics and ComputationalMathematics, Beijing, China) INST APPL PHYS & COMPUTAT MATH LAB COMPUTAT PHYSBEIJINGPEOPLES R CHINA

The multigrid algorithm in [13] is developed for solving nonlinear parabolic equations arising from the finite element discretization. The computational cost of the algorithm is approximate O(NkN) where N-k is the dim... 详细信息

关键词： Th Math A MULTIGRID METHOD FOR NONLINEAR PARABOLIC PROBLEMS UC

Preparation, Characterization and Luminescent Properties of MCM-41 Type Materials Impregnated with Rare Earth Complex

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Journal of Materials Science & Technology 2001年第3期17卷 293-298页

作者： Lianshe FU and Hongjie ZHANG Key Laboratory of Rare Earth chemistry and physics, Changchun institute of Applied chemistry, Chinese Academy of Sciences, Changchun 130022, China Philippe Boutinaud Laboratoire des Materiaux Inorganiques, UMR 6002, Universite Univ Blaise Pascal Lab Mat Inorgan UMR 6002 F-63177 Clermont Ferrand France ENSCCF F-63177 Clermont Ferrand France Chinese Acad Sci Changchun Inst Appl Chem Key Lab Rare Earth Chem & Phys Changchun 130022 Peoples R China

Hybrid materials incorporating Eu-(TTA)(3). 2H(2)O (7hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of EU3+ under UV light excitation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.

关键词： MCM Characterization and Luminescent Properties of MCM-41 Type Materials Impregnated with Rare Earth Complex Preparation