材料期刊网

Rheological Behaviour for Polymer Melts and Concentrated Solutions Part Ⅲ: A New Multiple Entanglement Model to Predict the Dependence of Linear Viscoelastic Function (η_0, Ψ_(10)~0,η_(ext)~0) on the Ranges of Primary Molecular Weights and the

Mingshi SONG and Jincai YANG (Research Institute of Polymeric Materials , Beijing University of Chemical Technology , Beijing , 100029 , China)Yiding SHEN(North West Institute of Light Industry , Shanxi Xianyang , 712087 , China)

材料科学技术（英文）

It is shown theoretically that the viscoelasticity of polymer melts is determined by three combining factorst they are the primary molecular weight and its distribution, the number of entanglement sites on polymer chain and the sequence distribution of constituent chains in entanglement spacings. A unified quantity for the three combing factors is the average constrained dimensional number of constituent chains in the long entanglement spacings (v). A new relation of v to the primary molecular weight and the number of testing polymers were derived from the multiple entanglement and reptation model, and a new method for determining v was proposed. The dependences of linear viscoelastic functions on the primary molecular weight and its distribution were derived by the statistical method. When Mn=6Me to 18 Me, the values of (v) can range from 3.33 to 3.70. Their values are in a good agreement with the experiment data, and it can slightjy vary with the different species of polymers and the different ranges of molecular weight of polymers

关键词:

University of Science and Technology Beijing

JIA Shizhen University of Science and Technology Beijing , China.

材料科学技术（英文）

关键词:

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

Mingshi SONG , Sizhu WU and Xiuyun DU(Research Institute of Polymeric Materials , Beijing University of Chemical Technology , Beijing , 100029 , China)

材料科学技术（英文）

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:

Abstracts of papers from Journal of University of Science and Technology Beijing

稀有金属（英文版）

关键词:

CORRELATION BETWEEN STRESS COMPONENTS AND STRESS CORROSION CRACKS IN BRASS Lecturer,Department of Materials Physics,University of Science and Technology Beijing,Beijing 100083,China

QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.

关键词: stress corrosion cracking , null , null , null

Huazhong University of Science and Technology(H.U.S.T)

材料科学技术（英文）

关键词:

欢迎投稿、订阅《Journal of Wuhan University of Technology-Materials Science Edition》

武汉理工大学学报-材料科学版(英文版)

关键词:

Titanium technology in the USA - an overview

D.Eylon , S.R.Seagle

材料科学技术（英文）

The state of Ti research, development and industry is reviewed in this article. The fifty-year anniversary of Ti technology commercialization in the USA provides an opportunity for a historical perspective. Incorporation of "information-age" tools into alloy development, processing, and production invigorates the technology. Consolidation, diversification and globalization have been transforming the Ti industry in the recent years.

关键词:

Theoretical Model of Steel Continuous Casting Technology

C Gheorghies , I Crudu , C Teletin , C Spanu

钢铁研究学报(英文版)

A theoretical model adapted for studying steel continuous casting technology was proposed. The model based on system theory contained input/output, command, and control parameters. The process was divided into five stages, ie, tundish, mold, guiding system, guidingdrawing system, and guidingdrawingsoft reduction system. The model can be used to describe the physicochemical processes, thermal processes, chemical processes, and characteristics of the cast material according to the abovementioned stages. It can also be applied to other metallurgical technologies and even to other industries (chemistry, food, etc).

关键词: steel;casting technology;system theory;modeling

Technology Development and Production of Certain Chemical Platinum Metals Compounds at JSC "Krastsvetmet"

ILYASHEVICH V.D. , PAVLOVA E.I. , KORITSKAYA N.G. , MAMONOV S.N. , SHULGIN D.R. , MALTSEV E.V.

贵金属

关键词: