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May 1991

Volume 35, Issue 4, pp. 467-716


Stability of a periodic unidirectional flow of viscoelastic fluids

M. A. Brutyan and P. L. Krapivsky

J. Rheol. 35, 467 (1991); http://dx.doi.org/10.1122/1.550230 (10 pages)

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We investigate the stability of a periodic unidirectional two‐dimensional flow of viscoelastic fluid. An exact value of the critical Reynolds number Rc is found for two models of a viscoelastic material: the upper convected Maxwell fluid and the Oldroyd B or Boger fluid.
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47.20.-k Flow instabilities
47.15.ki Inviscid flows with vorticity

Hydrodynamic lubrication theory for the Bingham plastic flow model

John A. Tichy

J. Rheol. 35, 477 (1991); http://dx.doi.org/10.1122/1.550231 (20 pages) | Cited 6 times

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When the shear stress magnitude of a Bingham material exceeds the yield shear stress, quasi‐Newtonian flow results, otherwise the material is rigid. The Bingham model has been used in tribology to describe the behavior of greases, but may also be used for electrorheological fluids proposed as ‘‘smart’’ lubricants. For two‐dimensional flow, different modified Reynolds’ equations are obtained, depending on the possible local formation of a rigid core which may be attached to either surface, or float between the surfaces. From the modified Reynolds’ equation it is straightforward to predict bearing behavior, patching together the different core formation cases. Results are presented for two geometries: the squeeze film damper and the journal bearing.
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81.40.Pq Friction, lubrication, and wear

Wall slip of molten high density polyethylene. I. Sliding plate rheometer studies

S. G. Hatzikiriakos and J. M. Dealy

J. Rheol. 35, 497 (1991); http://dx.doi.org/10.1122/1.550178 (27 pages) | Cited 27 times

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Experiments were performed in a sliding plate rheometer with a high density polyethylene to determine the conditions for the onset of slip and the relationship between slip velocity and shear stress. It was found that melt slip occurs at a critical shear stress of approximately 0.09 MPa in both steady and transient shear tests. The effect of the presence of a layer of fluorocarbon at the interface on both the slip velocity and the critical shear stress for the onset of slip, was also studied. Exponential shear was used to study the effect of shear history on slip. Both steady state and dynamic models for the slip velocity are proposed that are consistent with the experimental observations. Results of oscillatory shear experiments suggest that melt slip is a physicochemical process in which the polymer–wall interface undergoes continuous change during successive cycles.
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47.50.-d Non-Newtonian fluid flows

Viscosity of critical mixtures: Isopycnic polymer blendsa)

L. C. Cerny, E. L. Cerny, J. K. Sutter, and D. Czerniawski

J. Rheol. 35, 525 (1991); http://dx.doi.org/10.1122/1.550179 (13 pages)

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In many multicomponent systems, a transition from a single phase of uniform composition to a multiphase state with separated regions of different composition can be induced by changes in temperature and shear. The density difference between the phase and thermal and/or shear gradients within the system results in buoyancy driven convection. These differences affect kinetics of the phase separation if the system has a sufficiently low viscosity. This investigation presents more preliminary developments of a theoretical model in order to describe effects of the buoyancy‐driven convection in phase separation kinetics. Polymer solutions were employed as model systems because of the ease with which density differences can be systematically varied and because of the importance of phase separation in the processing and properties of polymeric materials. Isopycnic polymer solutions were used to determine the viscosity and density difference limits for polymer phase separation. From these methods, it was possible to examine polymer–polymer interactions in a θ solvent. The rheological measurements were extended to detect the phase separation and to define the critical temperature.
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64.75.-g Phase equilibria
47.27.T- Turbulent transport processes

Mesoscopic domain theory for textured liquid crystalline polymers

Ronald G. Larson and Masao Doi

J. Rheol. 35, 539 (1991); http://dx.doi.org/10.1122/1.550180 (25 pages) | Cited 18 times

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Here we present a mesoscopic theory of the low‐flow‐rate rheological properties of textured or polydomain samples of liquid crystalline polymers. In this theory, the Leslie–Ericksen equations are assumed to apply to each domain; these equations are averaged over a spatial region, large compared to a single domain, yet small compared to bulk dimensions. Along with these averaged equations, phenomenological expressions are postulated that allow us to obtain a relatively simple set of coupled equations for the domain size and the mesoscopic orientation and stress tensors. The values of the Leslie–Ericksen viscosities that appear in the equations are obtained from the Doi theory for nematic polymers. We apply the theory to several shear flows, namely recoverable shear after cessation of steady shearing, and step reversal and step increase of shear rate. In each case promising agreement is found between the predictions of the mesoscopic theory and measurements on lyotropic liquid crystalline polymers.
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61.30.Cz Molecular and microscopic models and theories of liquid crystal structure
61.41.+e Polymers, elastomers, and plastics
47.27.-i Turbulent flows
62.10.+s Mechanical properties of liquids

The effects of shielding on viscous drag forces operating on chain‐like macromolecules

S. S. Feng, R. C. MacDonald, and B. M. Abraham

J. Rheol. 35, 565 (1991); http://dx.doi.org/10.1122/1.550181 (23 pages)

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A theoretical analysis is developed to compute the extensional force exerted on a fully stretched macromolecule in an elongational flow of a given extensional strain rate. The long chain molecules are described by a bead‐on‐a‐string model. The dynamic problem in the external flow field is solved by the boundary collocation truncated series method. The total stretching force is then computed from the viscous stresses on the surfaces of each bead. This approach permits calculation of the magnitude of interbead shielding effects. Current practice for estimating stretching and fracture forces on macromolecules in elongational flow experiments involves application of Stokes law to each bead as though the flow around it were independent of that around the others. In the present analysis, an analytical expression for the shielding factor is developed. An approximate formula relating shielding effects to molecular weight is extracted from the results of numerical computation. Using this formula it is proved that the free‐draining Rouse model and the non‐free‐draining Zimm model represent opposite extremes with respect to shielding effects. Also, a more accurate power index in the relationship between relaxation time and molecular weight is given. A calculation is also carried out for spectrin, the protein molecule responsible for the elasticity of the red blood cell membrane, as an application example. On the basis of a chain of 40 beads separated by 50 Å and having a radius 12.5 Å, a shielding factor of 37% was calculated. Thus, even for this relatively short polymer, the neglect of shielding would overestimate the drag on its surface by a factor of 2.7.
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87.19.-j Properties of higher organisms
47.10.-g General theory in fluid dynamics
36.20.Fz Constitution (chains and sequences)

Accounting for lubricant shear thinning in the design of short journal bearings

A. Rastogi and R. K. Gupta

J. Rheol. 35, 589 (1991); http://dx.doi.org/10.1122/1.550182 (15 pages) | Cited 3 times

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Equations are derived for analyzing the flow of inelastic, non‐Newtonian lubricants in short journal bearings. A realistic bearing geometry is used along with the power‐law fluid model to study the influence of lubricant shear thinning on the load‐bearing capacity under isothermal conditions. The results are useful for designing journal bearings to achieve desired values of the friction coefficient or the minimum oil film thickness for steady as well as time‐varying loads. These results show that the idea of using the viscosity corresponding to the shear rate in the bearing for evaluating engine oil flow characteristics is a reasonable one.
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81.40.Pq Friction, lubrication, and wear

Viscoelastic flow in a periodically constricted tube: The combined effect of inertia, shear thinning, and elasticity

Stergios Pilitsis, Athanassios Souvaliotis, and Antony N. Beris

J. Rheol. 35, 605 (1991); http://dx.doi.org/10.1122/1.550183 (42 pages) | Cited 1 time

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The flow of a shear‐thinning viscoelastic fluid (Separan AP‐30) through a periodically constricted tube (PCT) is simulated using a mixed pseudospectral finite difference numerical method and a variety of constitutive equations. The results obtained with viscoelastic models show, at best, a small increase in the flow resistance beyond the value computed for a purely viscous inelastic fluid. The largest increase was observed with the modified Phan‐Thien–Tanner model. This model, in addition to fitting the standard viscometric data (viscosity and first normal stress difference), predicts a nonzero second normal stress difference and allows for dynamic behavior characterized by nonaffine deformation and stress overshoot in start‐up of shear flow. All the calculated values, although they show the correct tendency, are well below the experimentally measured values of Deiber and Schowalter (1981).
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62.60.+v Acoustical properties of liquids
47.60.-i Flow phenomena in quasi-one-dimensional systems

The Cox–Merz rule extended: A rheological model for concentrated suspensions and other materials with a yield stress

D. Doraiswamy, A. N. Mujumdar, I. Tsao, A. N. Beris, S. C. Danforth, and A. B. Metzner

J. Rheol. 35, 647 (1991); http://dx.doi.org/10.1122/1.550184 (39 pages) | Cited 16 times

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A nonlinear rheological model combining elastic, viscous, and yielding phenomena is developed in order to describe the rheological behavior of materials which exhibit a yield stress. A key feature of the formulation is the incorporation of a recoverable strain; it has a maximum value equal to the critical strain at which the transition from an elastic solid‐like response to a viscous shear thinning response occurs. An analysis is presented to enable determination of all the model parameters solely from dynamic measurements which are easily accessible experimentally. A rigorous correlation, analogous in form to the Cox–Merz rule, is shown to exist between the steady shear viscosity and the complex dynamic viscosity in terms of a newly defined ‘‘effective shear rate.’’ Experimental data obtained for a 70 vol % suspension of silicon particles in polyethylene indicate agreement with theoretical predictions for both the dynamic and steady shear behavior.
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62.60.+v Acoustical properties of liquids
47.55.-t Multiphase and stratified flows

Quasi‐Newtonian constitutive equations exhibiting flow‐type sensitivity

Gianni Astarita

J. Rheol. 35, 687 (1991); http://dx.doi.org/10.1122/1.550185 (3 pages)

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Abstract Unavailable
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47.27.W- Boundary-free shear flow turbulence
47.32.Ef Rotating and swirling flows
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Separated microphase structure and mechanical properties of blood‐compatible polyurethaneureas (abstract)

Yuko Ikeda, Shinzo Kohjiya, Shinzo Yamashita, Hisao Hayashi, and Tatsuya Okuno

J. Rheol. 35, 692 (1991); http://dx.doi.org/10.1122/1.550258 (1 page)

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Abstract Unavailable
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62.10.+s Mechanical properties of liquids
87.19.-j Properties of higher organisms
81.30.-t Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
61.25.H- Macromolecular and polymers solutions; polymer melts

Evaluation of differential constitutive equations based on stress relaxation data for polymer melts (abstract)

Masaoki Takahashi, Kaori Taku, and Toshiro Masuda

J. Rheol. 35, 693 (1991); http://dx.doi.org/10.1122/1.550186 (1 page)

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Abstract Unavailable
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61.25.H- Macromolecular and polymers solutions; polymer melts
46.35.+z Viscoelasticity, plasticity, viscoplasticity

Dynamic viscoelasticity of thermotropic liquid crystalline cellulose derivatives (abstract)

Tada‐aki Yamagishi, Takeshi Fukuda, Takeaki Miyamoto, Shigeru Yao, and Eiichi Kamei

J. Rheol. 35, 694 (1991); http://dx.doi.org/10.1122/1.550187 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.30.Eb Experimental determinations of smectic, nematic, cholesteric, and other structures
61.25.H- Macromolecular and polymers solutions; polymer melts

Effect of flow history on rheological properties of a thermotropic liquid crystalline copolyester (abstract)

Ken‐ichi Fujiwara, Masaoki Takahashi, and Toshiro Masuda

J. Rheol. 35, 695 (1991); http://dx.doi.org/10.1122/1.550188 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
47.27.-i Turbulent flows
61.30.-v Liquid crystals
61.25.H- Macromolecular and polymers solutions; polymer melts

Viscoelastic and flow birefringence studies of compatible polymer blends (abstract)

Seiichi Shibasaki, Eiichi Takatori, Tadashi Inoue, and Kunihiro Osaki

J. Rheol. 35, 696 (1991); http://dx.doi.org/10.1122/1.550254 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
78.20.Fm Birefringence
61.25.H- Macromolecular and polymers solutions; polymer melts

Thermoreversible sol–gel transition of low‐molecular weight gelling agents/polymer systems. II. Concentration dependence of gelling agents on the sol–gel transitions of isotactic polypropylene melt (abstract)

Toshiaki Kobayashi, Masaoki Takahashi, and Takeji Hashimoto

J. Rheol. 35, 697 (1991); http://dx.doi.org/10.1122/1.550189 (2 pages)

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Abstract Unavailable
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82.70.Gg Gels and sols
61.25.H- Macromolecular and polymers solutions; polymer melts
64.70.Ja Liquid-liquid transitions

Effect of additives on the stability of coal–water mixtures (abstract)

Hiromoto Usui

J. Rheol. 35, 698 (1991); http://dx.doi.org/10.1122/1.550190 (1 page)

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Abstract Unavailable
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64.75.-g Phase equilibria
66.20.-d Viscosity of liquids; diffusive momentum transport

Startup flow of viscoelastic fluids in a circular pipe under constant flow rates (abstract)

Noriyasu Mori, Hiroaki Takehara, Yoshiro Konishi, and Kiyoji Nakamura

J. Rheol. 35, 699 (1991); http://dx.doi.org/10.1122/1.550191 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
47.50.-d Non-Newtonian fluid flows

The longest relaxation time in semidilute polymer solutions (abstract)

Michio Wakutsu, Yoshiaki Takahashi, and Ichiro Noda

J. Rheol. 35, 700 (1991); http://dx.doi.org/10.1122/1.550192 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts

Dynamic viscoelasticity, stress relaxation, and elongational flow behavior of high density polyethylene melts (abstract)

Katsuyuki Yoshikawa, Nobuhiro Toneaki, Yoshihiro Moteki, Masaoki Takahashi, and Toshiro Masuda

J. Rheol. 35, 701 (1991); http://dx.doi.org/10.1122/1.550193 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts
47.27.-i Turbulent flows

Dynamic viscoelasticity and stress relaxation of column‐fractionated high density polyethylene melts (abstract)

Katsuyuki Yoshikawa, Nobuhiro Toneaki, Yoshihiro Moteki, Masaoki Takahashi, and Toshiro Masuda

J. Rheol. 35, 702 (1991); http://dx.doi.org/10.1122/1.550194 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts

Study on reaction and heat transfer of reactive polyurethane system for reaction injection molding (abstract)

Akihiko Koiwai, Takaaki Matsuoka, Hideroh Takahashi, Yorihide Kubota, and Hagemu Katoh

J. Rheol. 35, 703 (1991); http://dx.doi.org/10.1122/1.550195 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
82.35.-x Polymers: properties; reactions; polymerization
47.27.T- Turbulent transport processes

Electrorheological behavior of barium titanate suspensions (abstract)

Yasufumi Otsubo and Koichiro Watanabe

J. Rheol. 35, 704 (1991); http://dx.doi.org/10.1122/1.550196 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
62.10.+s Mechanical properties of liquids
82.70.Kj Emulsions and suspensions

Analysis of thermal expansion coefficients of composites reinforced with plane randomly oriented discontinuous carbon fibers (abstract)

Hogyu Yoon and Kiyohisa Takahashi

J. Rheol. 35, 705 (1991); http://dx.doi.org/10.1122/1.550197 (1 page)

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Abstract Unavailable
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65.40.De Thermal expansion; thermomechanical effects
81.05.Pj Glass-based composites, vitroceramics

Flow curves of mixtures of acrylonitrile–styrene copolymers with different molecular weights at extremely high shear rates (abstract)

Hideroh Takahashi, Yoshinori Inoue, Satoru Yamamoto, and Osami Kamigaito

J. Rheol. 35, 706 (1991); http://dx.doi.org/10.1122/1.550198 (1 page)

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Abstract Unavailable
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47.27.-i Turbulent flows
66.20.-d Viscosity of liquids; diffusive momentum transport
61.25.H- Macromolecular and polymers solutions; polymer melts

The long time relaxation of the microheterogeneous polymer liquids. I. General model (abstract)

Toshikazu Takigawa and Toshiro Masuda

J. Rheol. 35, 707 (1991); http://dx.doi.org/10.1122/1.550199 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts
66.20.-d Viscosity of liquids; diffusive momentum transport
66.10.C- Diffusion and thermal diffusion

Self‐diffusion and viscoelasticity of concentrated solutions of linear polystyrene in dibutyl phthalate (abstract)

Masahiro Kishine, Norio Nemoto, Tadashi Inoue, and Kunihiro Osaki

J. Rheol. 35, 708 (1991); http://dx.doi.org/10.1122/1.550200 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts
66.10.C- Diffusion and thermal diffusion

Influence of ionic strength on dynamic viscoelasticity of aqueous solutions of alginate/calcium complex (abstract)

Takayoshi Matsumoto, Hirofumi Zenkoh, and Tomoyasu Kaji

J. Rheol. 35, 709 (1991); http://dx.doi.org/10.1122/1.550201 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity

Piezoelectric relaxation phenomena in polymers (abstract)

Eiichi Fukada

J. Rheol. 35, 710 (1991); http://dx.doi.org/10.1122/1.550202 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
77.65.-j Piezoelectricity and electromechanical effects
61.41.+e Polymers, elastomers, and plastics

Extensional and fractural properties of polymers (abstract)

Eiichi Kamei

J. Rheol. 35, 711 (1991); http://dx.doi.org/10.1122/1.550203 (1 page)

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Abstract Unavailable
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46.50.+a Fracture mechanics, fatigue and cracks
62.20.M- Structural failure of materials
61.41.+e Polymers, elastomers, and plastics

Flow behavior of polymer melts under extremely high shear rates and flow analysis of injection molding (abstract)

Hideroh Takahashi

J. Rheol. 35, 712 (1991); http://dx.doi.org/10.1122/1.550204 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts
47.27.-i Turbulent flows

Applicability of the Leonov model to steady shear flow and stress relaxation after cessation of the flow for concentrated polymer solutions and melts (abstract)

Masaoki Takahashi, Kenichiro Ogawa, and Toshiro Masuda

J. Rheol. 35, 713 (1991); http://dx.doi.org/10.1122/1.550153 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts
47.27.-i Turbulent flows

Shear and elongational flows of CaCO3‐filled polystyrene melts (abstract)

Lin Li and Toshiro Masuda

J. Rheol. 35, 714 (1991); http://dx.doi.org/10.1122/1.550256 (1 page)

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Abstract Unavailable
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46.35.+z Viscoelasticity, plasticity, viscoplasticity
61.25.H- Macromolecular and polymers solutions; polymer melts
47.27.-i Turbulent flows

Drag reduction caused by the injection of polymer solutions into a pipe flow (abstract)

Hiromoto Usui

J. Rheol. 35, 715 (1991); http://dx.doi.org/10.1122/1.550154 (1 page)

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Abstract Unavailable
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47.27.T- Turbulent transport processes
61.25.H- Macromolecular and polymers solutions; polymer melts

Microphase separation in segmented polyurethaneureas based on poly(oxypropylene) containing poly(oxyethylene) segment (abstract)

Shinzo Kohjiya, Takafumi Yamato, Yuko Ikeda, Shinzo Yamashita, Yasuo Saruyama, Hisao Hayashi, Noboru Yamamoto, and Iwao Yamashita

J. Rheol. 35, 716 (1991); http://dx.doi.org/10.1122/1.550155 (1 page)

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Abstract Unavailable
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64.75.-g Phase equilibria
62.10.+s Mechanical properties of liquids
87.19.-j Properties of higher organisms
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