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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

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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.

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Mechanical, Thermal, Morphological and Rheological Properties of Polypropylene/Ultrahigh Molecular Weight Polyethylene Blends

Xiaodong WANG , Riguang JIN and Hangquan LI (Beijing University of Chemical Technology , Beijing , 100029 , China)

材料科学技术（英文）

In this study, the blends of polypropylene (PP) and ultrahigh molecular weight polyethylene (UHMWPE) were prepared by the four-and twin-screw extruders, and ethylene-propylene-diene monomer (EPDM), as the third component, was added to the binary blends. The mechanical.thermal, morphological and rheological properties of these two blends have been investigated.For the materials blended by the four-screw extruder, a 15 wt-% content of UHMWPE corresponds to a maximum lzod impact strength, and the miscibility enhancement effect of EPDM on PP/UHMWPE blends is very remarkable. Mechanical and thermal properties demonstrate that melt blending by the four-screw extruder is a better prcessing method for PP/UHMWPF blends than that by the twin-screw extruder. A co-continuous structure was observed in blends through TEM, and a novel "linear interpenetrating" toughening mechanism is proposed on the basis of this research work

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Study of Polymer Blends with Sub-cluster Theory Part I Essential Concepts and Equations of Sub-cluster Theory

Riguang JIN and Hangquan LI (Beijing Institute of Chemical Technology , Beijing , 100029 , China)(To whom correspondence should be addressed)

材料科学技术（英文）

Various viscosity-composition curves of polymer blends are summarized in eight groups. To represent these curves. "sub-cluster equations" are derived on the basis of so called "sub-cluster theoryThe essential concepts of sub-cluster theory and the derivation of those "Sub-cluster equations" are briefly introduced.

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Study of Polymer Blends with Sub-cluster Theory Part 2 Comparison of PVC/ABS, PVC/SBS Blends

Riguarng JIN and Hangquan LI(Bejing Institute of Chemical Technology , Beijing , 100029 , China)

材料科学技术（英文）

Series of PVC/ABS and PVC/SBS blends of composition 20/ 80. 40/ 60, 60 / 40 and 80 / 20were prepared in a screw extruder. The phase morphology, miscibility and rheological behaviour of two systems were investigated. The viscosity-composition plots were represented by sub-cluster equation, the various differences between two systems are interpreted with the equation parameters

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