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Dynamics of Polymeric Fluids：Part Ⅱ The Molecular Theory of Die Swell： Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

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Journal of Materials Science & Technology 2006年第5期22卷 664-676页

作者： Mingshi SONG Qiang XU Guixian HU sizhu wu Key Laboratory of Science and Technology of Controlled Chemical Reactions Beijing University of Chemical TechnologyBeijing 100029 China

A general expression for the correlation of the simple shear （tanφ） to the molecular parameters and the shear rate （·↑γ） was deduced. It shows that the simple shear （tanφ） may be resolved into free recoil （recoverable strain） and viscous heating （unrecoverable strain）. The magnitudes of the simple shears for recoil （tanφE） and （tanφv） for viscous heating not only depended on the molecular parameters and the operational variables, but also on the exponential fractions of the recoverable （1--↑W·↑γ） and unrecoverable （-↑W·↑γ） conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears （tanφE） for recoil and （tanφv） for viscous heating are, respectively, expressed as the partition function to the （1--↑W·↑γ）th power and the partition function to the （-↑W·↑γ）th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n′, α, η0, GN^0 and （1--↑W·↑γ）] and the operational variables （·↑γ, （L/D） and tr） were deduced respectively, which show that at very different shear rates （0≤·↑γ≤∞） the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=（L/D）], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n′, α, η0, GN^0 and （1--↑W·↑γ）] and the operational variables （·↑γ, （L/D） and tr） were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene （HDPE） which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.

关键词： Die swell Viscoelastic recoil Entanglement

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Dynamics of Polymeric Fluids 1. The Molecular Theory of Die Swell:A Set of Equation on Swelling Ratio in Extrudates

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Journal of Materials Science & Technology 2006年第1期22卷 93-107页

作者： Mingshi SONG Guixian HU Zhihong YANG Qiang xu sizhu wu Key Laboratory of Science and Technology of Controlled Chemical Reactions Beijing University of Chemical TechnologyBeijing 100029 China

The structural model of the multiple-transient networks and the mechanism of the multiple-reptation entangled chains due to the dynamic reorganization in the entangled sites were extensively applied on the die swell of polymeric liquids in the steady simple shear flow. The total （recoverable and unrecoverable） viscoelastic free energy of deformation and flow, the constitutive equation and the expression of the simple shear （tanψ） were deduced from the conformational probability distribution function of the entangled polymer chains. It found that：（1） the magnitudes of simple shear （tanψ） depended not only on the free recoil （or recoverable strain） but also on the viscous heating （or unrecoverable strain）; （2） the total recoil may be resolved into the instantaneous and delayed recoil. Based on these facts, the functions of the partition and two experiential fractions of the recoverable （1-Wγ） and the unrecoverable （Wγ） conformations for the recoil and viscous heating of polymeric liquids were defined correspondingly. Then the correlation of the instantaneously and ultimately （or total） recoverable strains to the （N1/T12）w and the fraction of trans-form conformation was obtained. After introducing the condition of uniform two-dimensional extension （αx=αy=α, αz=α^-2） and the swell ratio （B=α）, two sets of equations on the instantaneous and ultimate swelling ratios （BE, BEVT） were obtained, and a method to determine the fraction of the recoverable transform conformation were proposed, The equations of BE and BE5 were verified by the experimental data of HDPE （high denisity polyethylene） at two different high temperatures. It shows that the molecular theory of die swell can be used to predict the correlation of the swelling to the （NI/TI2）w and the fraction of trans-form conformation.

关键词： Die swell Entanglement Viscoelastic recoil

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Study on the gas permeabilities in styrene-butadiene rubber by molecular dynamics simulation

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Frontiers of Chemical Science and Engineering 2010年第3期4卷 257-262页

作者： Hailu LIU Xuejia DING Jun YI Liqun ZHANG sizhu wu College of Materials and Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China

In this research,molecular dynamics(MD)simulations were used to study the transport properties of small gas molecules in the butadiene-styrene copolymer(SBR).The condensed-phase optimized molecular potentials for atomistic simulation studies(COMPASS)force field was *** diffusion coefficients were obtained from MD(NVT ensemble)and the relationship between gas permeability;the chemical structure and free volume of butadiene-styrene copolymer were *** results indicated that the diffusion coefficient of oxygen declined with increasing styrene *** fraction of free volume(FFV)in butadiene-styrene copolymer was *** was concluded that diffusion coefficient increased as the FFV increases,which is in accordance with the analysis of the small molecular hop through the free volume in polymer ***,the glass transition temperatures of these copolymers were calculated by *** result showed that the glass transition temperature increased with increasing styrene content in polymer.

关键词： molecular dynamics SBR diffusion coefficient fraction of free volume glass transition temperature

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Rheological Behaviour for Polymer Melts and Concentrated SolutionsPart Ⅱ: Material Function with Nagai Chain Constraints and Determination of Their Parameters from Flow Curves

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Journal of Materials Science & Technology 1995年第2期11卷 141-152页

作者： Mingshi SONG sizhu wu and Xiuyun DU(Research Institute of Polymeric Materials, Beijing University of Chemical Technology, Beijing, 100029, China) Beijing Univ of Chemical Technology Beijing China

An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.

关键词： LDPE Material Function with Nagai Chain Constraints and Determination of Their Parameters from Flow Curves Rheological Behaviour for Polymer Melts and Concentrated SolutionsPart Flow GR

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Thermal decomposition of poly(ethylene terephthalate)/mesoporous molecular sieve composites

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Frontiers of Chemical Science and Engineering 2007年第1期1卷 50-54页

作者： RUN Mingtao ZHANG Dayu wu sizhu wu Gang Key Lab of Beijing City on Preparation and Processing of Novel Polymer Materials Beijing University of Chemical TechnologyBeijing 100029China College of Chemistry&Environmental Science Hebei UniversityBaoding 071002China

The nonisothermal and isothermal degradation processes of poly(ethylene terephthalate)/mesoporous molecular sieve(PET/MMS)composites synthesized by in-situ polymerization were studied by using thermogravimetric analysis in *** nonisothermal degradation of the composite is found to be the first-order *** iso-conversional procedure developed by Ozawa is used to calcu-late the apparent activation energy(E),which is an average value of about 260 kJ/mol with the weight conversion from 0%to 30%,and is higher than that of neat *** degradation results are confirmed with the nonisothermal process,in which PET/MMS showed higher thermal stability than neat *** polymer in mesoporous channels has more stability due to the protection of the inorganic *** results indicate that mesoporous MMS in PET/MMS composites improve the stability of the polymer.

关键词： poly(ethylene terephthalate) mesoporous molecular sieve thermal degradation kinetics

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Rheological Behaviour for Polymer Melts and Concentrated Solutions Part Ⅰ:A New Multiple Reptation Model to Predict the Nonlinear Visco-elasticity with Nagai Chain Constraints in Entangled Polymer Melts

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Journal of Materials Science & Technology 1995年第1期11卷 15-30页

作者： Mingshi SONG and sizhu wu(Dept. of Polymer Science, Beijing University of Chemical Technology Beijing, 100029, China)

An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results

关键词： Rheological Behaviour for Polymer Melts and Concentrated Solutions Part A New Multiple Reptation Model to Predict the Nonlinear Visco-elasticity with Nagai Chain Constraints in Entangled Polymer Melts

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Comparison between the preparation,structure and mechanical properties of long fiber reinforced thermoplastics and short fiber reinforced thermoplastic

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Engineering Sciences 2012年第6期10卷 83-88,96页

作者： Fang Kun Yang Jie wu sizhu Li Mei Ma Mingtu The Key Lab of Beijing on Novel Polymer Materials Beijing University of Chemical Technology Beijing Nashengtong Advanced Materials & Technology Co.Ltd. Thermoplastic Composites Manufacturing & Processing Technology Center Technology Center of Great Wall Motor Company Limited Key Laboratory of Automotive Safety Integration & Smart Control of Hebei Province China Automotive Engineering Research Institute Co.Ltd.

This article summarizes the comparison between the preparation, structure and mechanical properties of long fiber reinforced thermoplastics （LFT） and short fiber reinforced thermoplastics （SFT）. Both of the experiment and theory results showed that the mechanical properties of long glass fiber reinforced thermoplastics pellets （LGFRT） have been enhanced better than that of short glass fiber reinforced thermoplastics pellets （SGFRT） manufactured by molding procession. After regulation of the relative humidity by 50 % , the mechanical properties of 30 % （ weight percent） short glass fiber content in SFT （ SFT-PA6-SGF30 ） are similar to that of 40 % long glass fiber content in LFT. Howev- er, the density of the latter is about 17 % lower than that of the former. Thus, the corresponding weight of products is reduced by 13 % ;output rate is increased by 21% , and the cost is therefore significantly lowered. And it has the fol- lowing advantages： impact strength is increased by 87 % ; the proportion is reduced by 20 % ; molding cycle is short- ened by 10 % ;materials cost is saved by 20 % -30 % and the final total cost is saved by 30 % -40 %. So LFT （LFT-PP-LGF40） can replace SFT （SFT-PA6-SGF30） with the similar basic mechanical properties under normal tem- perature or 160 ℃ lower.

关键词： long glass fiber reinforced thermoplastics short glass fiber reinforced thermoplastics mechanical properties comparison

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数据挖掘和知识发现领域热点主题分析

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情报杂志 2010年第7期29卷 18-24页

作者：吴思竹中国科学院国家科学图书馆北京100190 中国科学院研究生院北京100049

利用词频分析、共词聚类分析、可视化等方法对Web of Science数据库1998～2009年间的数据挖掘和知识发现领域的研究文献进行分析,探讨该领域的研究热点主题及其间关联。

关键词：知识发现数据挖掘共词聚类聚类分析

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基于R2RML的STKOS超级科技词表RDF转换实现

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数据分析与知识发现 2018年第12期2卷 89-97页

作者：王颖吴思竹中国科学院文献情报中心北京100190 中国医学科学院医学信息研究所北京100020

【目的】实现STKOS超级科技词表从关系数据库到RDF数据的自动转换。【方法】构建STKOS超级科技词表语义描述模型,针对STKOS超级科技词表的数据存储情况和数据特点,分别建立将科技术语、规范概念、范畴类、来源概念和术语等从关系数据库... 详细信息

【目的】实现STKOS超级科技词表从关系数据库到RDF数据的自动转换。【方法】构建STKOS超级科技词表语义描述模型,针对STKOS超级科技词表的数据存储情况和数据特点,分别建立将科技术语、规范概念、范畴类、来源概念和术语等从关系数据库存储字段转换到RDF数据集的R2RML映射文档,并利用R2RML Parser工具执行自动批量转换。【结果】完成STKOS超级科技词表大规模发布数据的RDF转换,生成1.9亿RDF三元组,并存入Virtuoso数据库中提供SPARQL查询功能。【局限】R2RML的自定义谓词不够灵活,对于复杂数据结构需要进行预先拆分和转换。【结论】本文基于R2RML开展了STKOS超级科技词表的RDF转换实践,其映射方法可为其他关系数据库或叙词表的RDF转换提供参考。

关键词： R2RML STKOS超级科技词表 RDF

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Design and implementation of the STKOS quality-control system

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Chinese Journal of Library and Information Science 2015年第3期 38-49页

作者： Haixia SUN Danya LI Junlian LI sizhu wu Tiejun HU Qing QIAN School of Information Management Nanjing University Institute of Medical Information & Library of Chinese Academy of Medical Sciences

Purpose: The aim of this study is to develop and implement a quality-control system to ensure authority control of the different knowledge units for the Scientific & Technological Knowledge Organization Systems(STKOS).Design/methodology/approach: First, we analyzed quality-control requirements based on the construction of the STKOS Metathesaurus. Then we designed a quality-control framework, the task management and transfer mechanism, and a service model. Afterwards, we carried out the experiments to check the rules and algorithms used in the system. Finally, the system was developed, and gradually optimized during its ***: The quality-control system supports collaborative knowledge construction, as well as consistency checks of knowledge units with different granularity levels, including terminologies, relationships, and concepts. The system can be flexibly *** limitations: The system is oriented to an English-language knowledge organization system, and may not perform well with Chinese-language systems and *** implications: The system can be used to support the construction of a single knowledge organization system, as well as data warehousing and interoperable knowledge organization systems. Originality/value: The STKOS quality-control system not only focuses on content building for the knowledge system, but also supports collaborative task management.

关键词： Scientific & Technological Knowledge Organization

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