Pigment dispersion in a water based paint using amphoteric acrylic resins

Pigment dispersion in a water based paint using amphoteric acrylic resinsToshikatsu Kobayashi, Hiroyuki Kageyama, and Shouji Ikeda

Citation: Journal of Rheology (1978-present) 38, 746 (1994); doi: 10.1122/1.550485 View online: http://dx.doi.org/10.1122/1.550485 View Table of Contents: http://scitation.aip.org/content/sor/journal/jor2/38/3?ver=pdfcov Published by the The Society of Rheology Articles you may be interested in Development of palm oil-based UV-curable epoxy acrylate and urethane acrylate resins for wood coatingapplication AIP Conf. Proc. 1584, 164 (2014); 10.1063/1.4866125 Acrylic-based resin with favorable properties for three-dimensional two-photon polymerization J. Appl. Phys. 95, 6072 (2004); 10.1063/1.1728296 A study on pigment dispersing resins—The effect of resins terminated with carboxyl groups J. Rheol. 37, 549 (1993); 10.1122/1.550410 Rigidity of Settled Pigment Layers in Paints J. Appl. Phys. 9, 502 (1938); 10.1063/1.1710447 X rays used to study pigment degradation in Van Gogh painting Phys. Today

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Abstracts of manuscripts appearing inNihon Rheoroji Gakkaishi

(Journal of the Society of Rheology, Japan)Volume 21, 1993

© 1994 by The Society of Rheology, Inc.I. Rheo!. 38(3), May/lune 1994 0148-6055194/38(3)fi43f221$4.00 743


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744 JAPANESE ABSTRACTS

Structure and molecular mobility of thecarboxymethylpolysaccharide-metal complexes

Takayoshi Matsumoto and Hirofumi Zenkoh

Department ofPolymer Chemistry, Kyoto University, Kyoto 606, Japan

Synopsis

Structure and molecular mobility of complexes between carboxymethylpolysaccharides(carboxymethylcellulose and carboxymethylchitin) and alkaline-earth metal ions in aqueoussystems were studied by means of dynamic viscoelasticity, SAXS and NMR measurements. Thefrequency-dependent curves of the dynamic modulus measured with a cone-plate rheometer shift toa longer time-scale region with complex formation and can be superposed to a master curve by onlya horizontal shift. This means that the relaxation times lengthen by complexation and that thecomplexation is an intramolecular rather than an intermolecular process. The SAXS and NMRmeasurements revealed that the site for complexation is a cavity between the carboxyl group and thehydroxy group attached to the neighboring residue. A new molecular model for complexation waspresented.

Pages 5-10


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JAPANESE ABSTRACTS 745

Thermal expansion coefficients of unidirectional carbonfiberlPEEK composite made of commingled yarns

Hogyu Yoon, Kiyohisa Takahashi, and Kazuhisa Harakawa

Department of Materials Science and Engineering, Nagoya Institute ofTechnology, Gokiso-cho, Showa-ku, Nagoya 466, Japan

Synopsis

Unidirectional carbon fiber (CF)/poly(ether-ether-ketone) (PEEK) composite was manufacturedfrom the commingled yams composed of CF and PEEK filaments (this composite is named"commingled composite"). The thermal expansion coefficient (TEe) of the commingled compositewas measured and compared with that of CFIPEEK unidirectional composite made of prepregsheets (this composite is named "prepreg composite"). The minimum value ofTEC's parallel to thefiber direction was observed at around 150 °C for both specimens which were not thermally treated.This minimum disappeared after the thermal treatment at 230 °C for 30 min or the repeatingmeasurements (O°C -> 230°C, O°C -> 230 °C,...). While the TEC of the prepreg composite wasalmost independent of temperature, that of the commingled composite showed a remarkabledecrease at temperatures above the glass transition temperature (Tg ) of PEEK. This could beinterpreted in terms of the orientation distribution of carbon fibers in the commingled composite.The difference of longitudinal TEC's between heating and cooling experiments was attributable tothe temperature difference between the surface and the inner parts of the specimen. The TEC'stransverse to the fiber direction were scarcely influenced by the thermal history. The TEC'sincreased slowly below 100 °C and increased rapidly above 100 °C with increasing temperature.Theoretical predictions based on the extended equivalent inclusion method and on the classicallamination theory exhibited good agreement with experimental data. However, it could not bepredicted that the TEC's parallel to the fiber direction were depressed at around 30 °C. The causeof this discrepancy was supposed due to the temperature dependence of TEC' s of the carbon fiberitself.

Pages 11-17

Bound water at sol-gel transition in bilayer aqueoussystems of egg lecithin

Takayoshi Matsumoto


Synopsis

The relationship between sol-gel transition and bound water in bilayer aqueous systems of egglecithin (EL) was studied by means of rheological, NMR and dielectric measurements. The viscosityand rigidity of the systems increase very sharply at the critical gel concentration c*, and thereciprocal value of the spin-lattice relaxation time of the water proton, Ti 1, which is proportionalto the correlation time of molecular motion, also increases sharply at c*.This means that the boundwater is strongly related to the sol-gel transition of the bilayer aqueous systems of EL. It wasconfirmed by the dielectric measurements that there were three types of bound water whosecharacteristic dielectric relaxation times are 2.0XlO- 8 s, 2.3XIO-9 sand 2.5X10-10 s.

Pages 18-22


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Pigment dispersion in a water based paint usingamphoteric acrylic resins

Toshikatsu Kobayashi

Research Center, Nippon Paint Co., Ltd., 19·17, Ikedanaka, Neyagawa,572 Osaka, Japan

Hiroyuki Kageyama

Automotive Coatings, Nippon Paint Co., Ltd., 19-17,Ikedanaka,Neyagawa, 572 Osaka, Japan

Shouji Ikeda

Research Center, Nippon Paint Co., Ltd., 19·17, Ikedanaka, Neyagawa,572 Osaka, Japan

Synopsis

Pigment dispersion in acid-neutralized water soluble acrylic resins which have both acidic and basicfunctional groups was studied. The dispersibility was evaluated by the gloss and the yield value ofthe pastes. As for the dispersion of a positively charged pigment, an excellent dispersibility of thepigment was obtained by the resin adsorption through electrostatic interaction between positivecharge of the pigment and negative charge of the resins when the acid strength of the resin washigher than that of the neutralizing acid. On the other hand, when the acid strength of theneutralizing acid was higher or a negatively charged pigment was used, no effect on the introductionof the acidic functional group to the resins was observed.

Pages 23-28


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JAPANESE ABSTRACTS

Mechanical properties of artificial teeth

Yoshio Shirasaki and Tetsuya Tateishi

747

Mechanical Engineering Laboratory, Namihi-L, Tsukuba, Ibaraki 305,Japan

Kazuhiro Shimoyama

Faculty of Dentistry, Tokyo Medical and Dental University, Yushima1-5-45, Bunkyo-ku, Tokyo 113, Japan

Synopsis

The purpose of this study was to investigate the mechanical properties of resin and porcelain teeth.

The static tests were performed with an Instron-type universal testing machine. The dynamic

stiffness and tan 8 were measured by using a viscoelastic spectrometer. The impact tests were

carried out with a drop weigh impact testing apparatus. Following results were obtained: (I) The

fracture load, ultimate strength, absorbed energy, and deformation in the static tests were larger for

the resin teeth than for the porcelain teeth. However, the elastic modulus was larger for the porcelain

teeth. (2) The stiffness measured dynamically was larger for the porcelain teeth than for the resin

teeth. The tan owas larger for the resin teeth. (3) The impact tests showed that the absorbed energy

and deformation were larger for the resin teeth, while the acceleration peak value was larger for the

porcelain teeth.

Pages 29-32

Velocity measurement in the startup flow of viscoelasticfluids through contraction with rectangular

cross-section

Noriyasu Mori, Takumi Kaige, and Kiyoji Nakamura

Department ofMechanical Engineering, Osaka University, Suita,Osaka 565, Japan

Synopsis

The unsteady viscoelastic flow generated by the sudden application of a constant flow rate is

experimentally examined for an abrupt contraction and a tapered one with a rectangular

cross-section. The velocity change with time is measured with a L.D.V. for a 1.0 wt % aqueous

solution of polyacrylamide. The gentle overshoot in the centerline velocity, which may be due to the

effect of extensional flow, is observed from the vicinity of the entrance of a small slit to the

downstream far from the entrance. Furthermore it is found that the flow in the entrance region

finally reaches the anomalous three dimensional flow with a dual peak form of the velocity profile.

Pages 33-40


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Estimate of the fluid force related to washing mechanism1 measurement of the drag of fine wires on a plate

caused by the flow of aqueous solutions of surfactant anddilute aqueous solution of polymer

Keiko Amaki

Faculty ofEducation, Iwate University, Ueda Morioka, Iwate 020, Japan

Tomiichi Hasegawa and Masaaki Konno

Faculty of Engineering, Department of Mechanical and ProductionEngineering, Niigata University, Ikarashi Niigata 950-21, Japan

Synopsis

The effect of fluid force on detergency has been experimentally investigated. More than onehundred wires of 50 J.l.m in diameter, as a model of two dimensional soil, were set so as to adhereto a bottom flat plate of a two dimensional channel. The aqueous solution of surfactant and thedilute aqueous solution of polymer were made to flow through the channel and the pressure dropcaused by the wires was measured. The drag and the drag coefficient (CD) of one wire wereestimated with the pressure drop by the use of the law of momentum. The following results areobtained. For all solutions used, the drag increases and the drag coefficient decreases with anincrease in the Reynolds number based on the wire diameter taken as the characteristic referencelength. The solution of LAS, one of familiar anionic surfactants, gives CD values lower than thepure water, and the difference becomes marked as the concentration of the solution increases. Anonionic surfactant solution, AE 1.0%, shows a time dependent character; it provides about half ofthe corresponding CD value of water within a day since the solution was produced, while it givesnearly the same as that of water after 4 days have passed. The CD for dilute solution of polymer(PEO 20 ppm) in water is higher than those for water and surfactant solutions. Viscosities of thesolutions tested were Newtonian and the magnitudes are in the same order for all three solutions.

These results suggest that the variation of CD observed for the three solutions is not directly relatedto the solution viscosity but probably to other properties such as elastic force.

Pages 41-47


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JAPANESE ABSTRACTS

Extension of uneven flat films

Susumu Kase

Department of Polymer Science and Engineering, Kyoto Institute ofTechnology, Sakyoku Matsugasaki, Kyoto 606, Japan

Synopsis

749

Extension of flat films uneven in thickness and lying on the (x,y) plane is analyzed mathematically.Constitutive models assumed are isothermal Newtonian fluids and rubber-like elastic solids.Governing equations reduce to the Cauchy-Riemann equations when the material is Newtonianfluid and the film is uniform in thickness. Many unusual modes of extension exist in this case. Inboth cases of Newtonian fluids and rubberlike elastic solids, governing equations reduce to readilysolvable ordinary differential equations when the extension is axisymmetrical. Conditions ofwrinkle free extension are introduced. Numerical solutions are obtained for the general extension ofthe films of rubber-like elastic solids.

Pages 61-73

Rheological behavior of liquid crystal pitch and its effecton the structure of carbon fiber

Ryuichi Hara

Analysis Laboratory, Research Center, Mitsubishi Kasei Corporation,1000, Kamoshida-cha, Midori-ku, Yokohama 227, Japan

Synopsis

The viscosity and viscoelasticity of a molten liquid crystal pitch were investigated by a cone-platetype rheometer at various temperatures. The molten material's viscous behavior was characterizedby WLF-type temperature-dependence and pseudoplastic flow. Furthermore, the material'sviscoelastic behavior was marked by two relaxation mechanisms at different angular frequencies.The mechanism with a longer relaxation time was observed in the lower angular frequency. It waspresumed that this was due to some higher order structures in the liquid crystal pitch resulted fromthe dependences of the dynamic storage modulus on the temperature, the shear history and thedegree of the heat treatment etc. The other mechanism with a shorter relaxation time, T, wasobserved in the higher angular frequency that corresponded to the glass transition. To investigate theeffect of T on the property of carbon fiber, the spinning process of the pitch fiber was simulated. It

was found that the Deborah number ND' defined by the ratio of T to the representative time scaleof the spinning process t r , determined the preferred orientation and crystallinity of the pitch fiberand the carbon fiber.

Pages 74-85


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Viscoelasticity and birefringence of bisphenol apolycarbonate 2. Stress relaxation measurement

Hirotaka Okamoto, Eui Jeong Hwang, Tadashi Inoue, and Kunihiro Osaki

Institute for Chemical Research, Kyoto University, Uji, Kyoto 611,Japan

Synopsis

The stress relaxation and simultaneous birefringence variation were measured for bisphenol Apolycarbonate over the glassy to the rubbery plateau regions. The measurements were performed atvarious temperatures of 142-156 °C over the time range of 0.4 to 2000 s. Results of relaxationmeasurements were consistent with those of dynamic measurements with respect to thebirefringence as well as the stress in the framework of linear viscoelasticity. A modifiedstress-optical rule was applied to the results of relaxation measurements. This rule was earlierproposed to replace the stress-optical rule which was suitable only in the rubbery and the terminalflow regions. The relaxation modulus, E(t), was separated into two component functions, ER(t)

and E G( t). In constructing master curves of ER(t) and E G(owith the method of reduced variables,their shift factors were found to have different temperature dependence. This result can account forthe break down of time-temperature superposition principle for E(t) reported by severalinvestigators. The present modified stress-optical rule was more convenient in several wayscompared with the similar modifications proposed earlier by Priss et aI. and Read.

Pages 86-90


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JAPANESE ABSTRACTS

Simulation of melt spinning of pitches

Toshikazu Takigawa

Research Center for Biomedical Engineering, Kyoto University,Kyoto 606, Japan

Masaoki Takahashi

751


Yuji Higuchi

Fundamental Research Laboratories, Osaka Gas Co., Ltd., Konohana-ku,Osaka 554, Japan

Toshiro Masuda

Research Center for Biomedical Engineering, Kyoto University,Kyoto 606, Japan

Synopsis

Effects of process variables and material properties on melt spinning of pitches have been studiedbased on simulation using governing equations by Kase and Matsuo. It is shown that the tension Fin a filament depends on spinning conditions as well as viscosity of pitch in the fonn of

FIX 1J.owIl6f,(vO,VL,VA)I!2(To,Ts ,TA ,E). Here, W, vo, VL, and VA are mass flow rate,velocity at the spinnerette, winding speed and cross-flow air velocity respectively, and To, Ts, andTA denote temperatures at the spinnerette, at the solidification point and of air. Temperaturedependence of viscosity is simplified by an Arrhenius type equation with a pre-exponential factor 1J.oand a flow activation energy E. To improve spinnability, the maximum tensile stress UL should be

decreased by increasing W, To and TA or by decreasing vL' VA, Ts, 1J.o and E. In other words,slower cooling of the filament with larger diameter for a pitch with smaller activation energy ispreferable to better spinnability. Effects of these factors on diameter, temperature and strain rate ofthe spinning filament are also discussed.

Pages 91-96


10:54:57


Application of pulse strain as a method of viscoelasticmeasurement

Misao Horigome

Central Research Laboratories, Dainippon Ink and Chemicals, Inc.,631 Sakato, Sakura, Chiba 285, Japan

Yasufumi Otsubo

Department of Image Science, Faculty ofEngineering, Chiba University,1-33 Yayoi, Inage, Chiba 263, Japan

Takenobu Isoda

Kawamura Institute of Chemical Research, 631 Sakato, Sakura,Chiba 285, Japan

Synopsis

Pulse Strain Method for viscoelastic measurements is presented, which is based on the RaisedCosine Pulse Method (RCP Method). According to the RCP Method, frequency dependence ofcomplex shear modulus is given by the Fourier transform of shear stress as the response to a pulsestrain of cosine type. However, frequency range of observation is limited to only I or 2 decades inlower region of fundamental frequency of applied pulse strain. To expand the frequency range, wehave modified the RCP Method using Rectangular Pulse Strain, which includes high-frequencycomponents (RAP Method). Comparison among the RCP Method, RAP Method and conventionaldynamic methods was made on a 20% polystyrene solution in diethylphthalate. In the case of theRAP Method, frequency range was expanded to higher frequencies of fundamental frequency ofapplied pulse strain compared with the RCP Method. Computer simulation of Pulse Strain Methodwas made to know the requirements for further expansion of frequency range. The shear stress asthe response to pulse strain was calculated for a Maxwell model using the Boltzmann superpositionprinciple, and then complex shear modulus was calculated from Fourier transform of pulse strainand shear stress. The obtained shear modulus from simulation was compared with the theoreticalvalue. It has been shown that resolution and response time of a torque transducer are important tomake the best use of Pulse Strain Method. The requirements for a torque transducer are as follows,resolution is IflOOOO, and response time is 0.1 ms,

Pages 97-102


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JAPANESE ABSTRACTS

Numerical simulation of contraction and expansionflows of fiber suspensions

Kazunori Yasuda, Kiyoji Nakamura, and Noriyasu Mori

Department of Mechanical Engineering, Osaka University, Suita,Osaka 565, Japan

Synopsis

753

Flow patterns and fiber orientations in the two-dimensional contraction and expansion flows of fibersuspensions are calculated using Dinh-Armstrong model. The assumption that all fibers lie tangentto a streamline is excluded from the present calculation. Therefore the Jeffery's equation isintegrated along a streamline to obtain the fiber orientation. The flow pattern of fiber suspension isdifferent from that of Newtonian fluid: a vortex near the comer in the suspension flow becomeslarger than that in the Newtonian flow.The dependence of the vortex length on a parameter a, whichis a characteristic parameter of fiber suspensions" and on Reynolds number is discussed. In thecontraction flow, fibers lie tangent to a streamline in the main flow, but not in the vortex region. Inthe expansion flow, however, fibers rotate along a streamline, so fibers do not lie tangent to astreamline even in the main flow. Furthermore, stress-relief-mechanism causes increase of thevortex in both flows.

Pages 103-109

A description of chain slippage across the slip-link in thedynamics of entangled linear polymers

Kwang Man Kim, Bong Ryuel Ryu,a) and In Jae Chung'"

Department of Chemical Engineering, Korea Advanced Institute ofScience and Technology, 373-1 Kusong, Yusong, Taejon 305-701, Korea

Synopsis

A mechanism of chain slippage across the entanglement link is adopted to describe the early stagebehavior in the stress relaxation of concentrated polymer systems. The chain slippage in thepostulated mechanism occurs due to the equilibration of natural monomer (Rouse bead) densities

between the primitive segmental units. It is shown that the process X introduced by Lin can beconfirmed theoretically and that it partially contributes to the reduction of stress discrepancy

between the processes A and B of Doi.

Pages 110-116

alDepartment of Polymer Engineering, Chonnam National University, Kwangju 500-757, Korea.blTo whom all correspondence should be addressed.


10:54:57


Numerical study on abrupt contraction How ofviscoelastic Huids including the inertia effect

Shuichi Tanoue, Toshihisa Kajiwara, and Kazumori Funatsu

Department of Chemical Engineering, Kyushu University, 6-10-1Hakozaki, Higashi-ku, Fukuoka 812, Japan

Synopsis

The viscoelastic flow in a planar abrupt contraction was analyzed including the inertia effect, andthe effects of inertia and viscoelasticity on the flow were studied. The Galerkin finite elementmethod was employed as the numerical method. The constitutive model was the simplifiedCriminale-Ericksen-Filbey (CEF) model which expressed the extra stresses as an explicit functionof velocity and deformation rate. We studied the effects of the Reynolds number, the Weissenbergnumber (the primary normal stress difference) and the elongational viscosity individually on there-entrant corner vortex and the entrance pressure drop. As a result, we found the following: (1) asthe primary normal stress difference increases, the corner vortex grows up but the entrance pressuredrop slightly decreases. (2) The inertia effect reduces the comer vortex produced by theviscoelasticity and increases the entrance pressure drop. (3) The flow fields are significantlyinfluenced by the viscoelasticity in the low flow rate region but become to be dominated by theinertia with increasing flow rate. (4) Both the vortex intensity and the entrance pressure drop for thefluid with strain-thickening elongational viscosity are larger than those for the fluid withstrain-thinning elongational viscosity.

Pages 123-129


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High Weissenberg number simulation of die swell fordifferential type viscoelastic model by the streamline

upwind finite element method

Yoshifumi Kuwano, Toshihisa Kajiwara, and Kazumori Funatsu

Department of Chemical Engineering, Kyushu University, 6-10-1Hakozaki, Higashi-ku, Fukuoka 812, Japan

Synopsis

In order to predict the die swell seen in the actual polymer processing, the planar, the capillary andthe annular die swell simulations have been performed by the streamline-upwind finite elementmethod with the subelements for stress components, which was shown effective to calculate up tohigh Weissenberg number (We) for the entry flow simulation in an earlier study. The calculationusing the Giesekus model, which is the differential type viscoelastic model, was found feasible overhundreds of We in the planar and the capillary die swell simulations as long as the primary normalstress difference was not so large. The shape of free surface at high We under the condition of nogravitation once showed the maximum swell and became an equilibrium one after shrinking backa little. This tendency became remarkable for the model with larger We and larger primary normalstress difference. Through the examination of the velocity profile, it was found that the velocity nearthe free surface was accelerated during the swell after extrusion and was larger than the insidevelocity in the neighborhood of the position which showed the maximum swell. Since theaccelerated outer fluid dragged the inside fluid, the swelling ratio was supposed to take anequilibrium value after shrinking back a little. Also, as the primary normal stress difference becamelarger, the axial position of the maximum swell approached the die. This may be due to that themodel with the large primary normal stress difference predicts faster swell, because the elasticrecovery force after extrusion is large. The axial position of the maximum swell became distantfrom the die with increasing We. We interpreted that the axial position of the maximum swell shifteddownstream as the representative relaxation time was longer, or the velocity became larger. On theother hand, the calculation became impossible for We > 3 in the annular die swell simulation. Inorder to examine this reason, we performed the calculation for the planar die swell in two differentanalysis regions, i.e., one being the whole flow region with two singular points and the other, thehalf flow region with one singular point in consideration of flow symmetry. The calculation in thewhole flow region with two singular points was unsuccessful at high We. It seems that the presenceof two singular points in the analysis region made it impossible to perform the annular die swell upto high We simulation.

Pages 130-137


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Viscosity of nonaqueous and aqueous alumina slurry fortape casting

Beyong-hwan Ryu and Suguru Suzuki

Ceramics Research Laboratory, Nagoya Institute of Technology, 10-6,Asahigaoka, Tajimi Gifu 507, Japan

Synopsis

This paper reports shear rate dependence of the viscosity and relative viscosity of highly

concentrated nonaqueous and aqueous slurries used for tape casting of the alumina sheet by a doctor

blade method. The nonaqueous and aqueous slurries containing 28-35 vol% and 24-29 vol%

alumina, respectively, were prepared by ball milling for this work. Approximate equations, derived

from the Dougherty-Krieger equation, log 71r = ad: and log 71r = a¢+(aJ2¢m)¢2, are both fitted

to the data measured quite well.

Pages 138-141

Laminar boundary layer of non-Newtonian flows withnetwork theory-Shear thinning characteristics

Hiroshi Yamaguchi

Department ofMechanical Engineering, Doshisha University, KarasumaImadegawa, Kyoto 602, Japan

Synopsis

Flows of non-Newtonian fluids passing a flat external surface with zero incidence angle was studied

theoretically. The constitutive equation used in the present study is the Phan Thien-Tanner (PTf)type with the network theory, and the simple power law is used for comparison. The thickness of

the boundary layer and the friction coefficient are calculated in order to examine the effects of the

breakage index and the slip parameter in the shear behavior. The Von Karman integral equation is

solved numerically with a similar solution of the velocity profile using the newly defined shape

factor. The calculation results for shear thinning liquids indicate that the thickness of the boundarylayer and the friction coefficient are dependent upon the slip parameter and the breakage index,

where a choice of nonzero breakage index without the effect of the normal stress terms yieldssimilar results to the power law case. It is revealed that the friction coefficient (wall shear stress) has

a peak value at the entrance region of the plate, whereas such a symptom is not seen in the case of

the power law and the Newtonian flows.

Pages 142-148


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JAPANESE ABSTRACTS

A simulation system for viscoelastic properties ofpolydisperse polymer melts

Shigeru Yao, Tatsuya Shoji, and Eiichi Kamei

Hirakata Laboratory, Corporate Research & Development, UbeIndustries, Ltd., 3-10, Nakamiya Kita-machi, Hirakata 573, Japan

Masaoki Takahashi

757


Synopsis

A simulation system is developed for evaluating viscoelastic properties of polymer melts witharbitrary polydispersity in molecular weight, starting from the known chemical structure of thepolymers. The critical molecular weight for entanglement and molecular weight dependence of zeroshear viscosity are evaluated based on theories of van Krevelen and Berry-Fox by optimizingparameters associated with chain flexibility, chain length and effective molar weight per repeatingunit. In the evaluation of viscoelastic properties of polymer melts, simple and reasonable shape ofrelaxation spectrum is assumed for polydisperse systems. Using molecular parameters evaluatedabove, frequency dependence of viscoelastic functions is calculated from the relaxation spectrum.This method is shown to be superior to the usual way of calculation of viscoelasticity based onblending rules: The time needed for the calculation is very short and does not depend on thepolydispersity in molecular weight. Combination of the present method with an appropriateconstitutive equation gives a system for evaluating nonlinear viscoelastic properties of polydispersepolymers.

Pages 149-155


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Ultradrawing of ultrahigh molecular weightpoly(acrylonitrile)

Tsunenori Kameda and Tetsuo Kanamoto

Department ofApplied Chemistry, Science University of Thkyo,Kagurazaka, Shinjuku-ku, Tokyo 162, Japan

Synopsis

Dry gel films of ultrahigh molecular weight poly(acrylonitrile) homopolymer, having strongintermolecular forces, have been drawn by solid-state coextrusion in the temperature range fromroom temperature to 260 "C. The effects of solution concentration from which gel was made andextrusion temperature on the extrusion behavior and the structure and properties of drawn filmshave been studied. The drawability of each gel increased with extrusion temperature above the Tg(80°C), reached a maximum at 160 °C, and then decreased rapidly above 160°C. The drawabilityof gel also increased with decreasing the solution concentration from which gel was generated. Thisindicates that the ductility of poly(acrylonitrile), which has strong intermolecular forces and exhibitsno crystalline relaxation, is also controlled by the entanglement density, like polyethylene havingweak intermolecular interactions. Gel prepared from the lowest concentration of 2 wt % in this workcould be extrusion-drawn to draw ratios ,,;; 82 at 160 °C. Extrusion temperature markedly affectednot only the ductility of gel, but also the efficiency of draw and the formation of flaws at high drawratios. Thus, the maximum tensile modulus and strength achieved in this work were 20 and 1.0 OPa,respectively.

Pages 156-162

Measurement of pressure loss in the flow of polymersolutions through packed beds of particles

Takashi Koshiba

Department ofMechanical Engineering, Nara National College ofTechnology, Yamato-Koriyama, Nara 639-11, Japan

Noriyasu Mori and Kiyoji Nakamura

Department ofMechanical Engineering, Osaka University, Suita, Osaka565, Japan

Synopsis

Flow behavior of polymer solutions through packed beds of particles, which are used as a model ofporous media, is experimentally examined. Two packing patterns are prepared and the test fluidsused here are aqueous solutions of polyacrylamide (PAA) at three different concentrations. In themeasurement of pressure loss, it is observed that the curve of pressure loss makes a sudden changeat the critical flow rate. Below the critical flow rate, the pressure loss depends on the shear propertyof the fluids and can be expressed by the modified Darcy's law applying the power law model to theshear viscosity of fluids. Beyond the critical flow rate, however, the transient elongational propertyof the fluids dominates the flow behavior in packed beds of particles and yields the excess pressureloss for the PAA solutions.

Pages 163-169


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Rheological properties and attenuation process in meltspinning of liquid crystalline pitch

Haruo Shikuma

Idemitsu Kosan, Central Research Laboratory, Sodegaura 299-02, Japan

Kiyohito Koyama

Department of Materials Science and Engineering, Yamagata University,Yonezawa 992, Japan

Synopsis

An experimental study for petroleum liquid crystalline pitch materials has been carried out to clarify

the relationship between rheological properties and melt spinning process. The softening

temperature, specific heat, viscosity, and dynamic moduli were measured. The flow activation

energy was obtained to be 55 kcallmol from the viscoelastic measurements. The attenuation process

in melt spinning occurred only close to the spinneret. The stress growth of the running filaments was

calculated by using the Bogue-White constitutive model. The experimental data were explained

well with a single relaxation time of 0.01 sec and non-linear parameter of 0.5. Spinnability was

inversely correlated to the relaxation time for the liquid crystalline pitch.

Pages 170-174

Numerical simulation of three-dimensional flow forinjection molding process

Yoshinori Inoue and Takaaki Matsuoka

Toyota Central Research and Development Laboratories, Inc., 41-1,Yokomichi, Nagakute, Aichi 480-11, Japan

Synopsis

A computer program to simulate three dimensional flow in injection molding process has been

developed. To investigate numerical methods of moving free surfaces of the flow, the flow in

injection molding process is regarded as isothermal, incompressible, high viscous flow of a

Newtonian fluid with free surfaces. Generally, many computing times and computer memories arespent for numerical calculation of high viscous flow with free surfaces. Therefore, an effective

combined calculation method was developed by using the two-stages rational Runge-Kutta scheme

for time integration, the pseudo concentrations method for calculation of the moving free surfacesand the donor-acceptor scheme for an advection equation of the pseudo concentrations to reduce the

computational effort in the computer program. A numerical calculation was carried out for the mold

filling simulation in a cavity composed of a plate and a cylinder. This calculated result was

compared with the experimental result which was obtained by an observation of filling flow ofsilicone oil in a visible cavity. As a result, the calculated flow patterns agreed with the observed

ones.

Pages 175-180


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Application of the raised cosine pulse method to thesystems having yield stress

Takoyoshi Matsumoto

Department of Polymer Chemistry, Kyoto University, Kyoto 606, Japan

Keiko Katsuta

Department ofLife Science, Niigata University, Ikarashi-nino-cho,Niigata 950-21, Japan

Youichi Miyamoto

Rheology Engineering, 1-293, Ohe-nakayama-cho, Saikyo-ku,Kyoto 610-11, Japan

Synopsis

Dynamic viscoelasticity of the systems having yield stress was measured using the raised cosinepulse (RCP) method by means of a cone-plate type rheometer. The systems employed weremayonnaise and ketchup which are typical plastic materials. Influence of the amplitude of RCPstrain on the convergence of the response stress was investigated. The response stress for a largeRCP strain does not converge to zero. That is, the stress has a finite negative value still after a longtime. In this case, the Fourier transformation of the response stress cannot be performed with asatisfied accuracy. On the other hand, the response stress converges to zero within a very short timefor a small RCP stain and the frequency dependences of the dynamic moduli can be obtained, whichare sufficiently congruent to them by the usual dynamic measurement.

Pages 181-183


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Flow behavior of high polymers and its application topolymer processing

Yasushi Oyanagi

Kogakuin University, Nishishinjuku, Shinju-ku, Tokyo 160, Japan

Synopsis

This report extensively summarized a series of researches on the properties, especially flowbehavior, of high polymeric materials concerning the polymer processing made by the author of thispaper and his co-workers. Since the high polymeric materials are in most cases viscoelastic, theyshow a lot of peculiar and diverse flow behaviors. In this paper, various types of the peculiaritiesand problems in the flow behavior of the polymer melts, such as melt viscosity characteristics, meltfracture, and p-u-T characteristics are discussed. Flow characteristics has long been known to beone of the most fundamental properties governing the polymer processing operation. In recentyears, many researchers found the great importance of the pressure effect on the melt flowproperties and cooling effect on the mechanical properties of the products. As a result, it will be oneof the research trend to study the p-u-T state characteristics of the high polymer, which would givea clear explanation to the above mentioned effects. The matter the author wishes to emphasizethroughout this paper is that the rheology has a close relationship with polymer processing and

many problems in the polymer processing can be solved through detailed rheological investigations.Thus the author and his co-workers will find it a great pleasure if their researches on polymerprocessing will be helpful in the progress of polymer technology. Finally, the author is deeplyindebted to many distinguished researchers and outstanding scientists for promotion of theresearches mentioned above.

Pages 209-217


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Studies on constitutive equations for polymer liquids

Masaoki Takahashi

Division of Material Chemistry, Faculty ofEngineering, Kyoto University,Kyoto 606-01, Japan

Synopsis

Studies on integral and differential constitutive equations by the present authors are summarized andsome new results are presented. Applicability of various constitutive equations to some typicaldeformation modes is investigated. In integral equations, superiority of the BKZ model isestablished. But it is also known that the model fails in a prediction of stress relaxation fordouble-step shear strains in which the second step strain is applied in the opposite direction to thefirst. A stress dependent constitutive model of integral type proposed by the present authors candescribe this double-step stress relaxation very well as well as ordinary single-step stress relaxationand shear rate dependence of viscosity. Compared to integral equations, applicability of differentialequations is limited. The Leonov model is very useful to predict viscoelastic functions in steadyshear flow, but it fails in describing both stress relaxations for a step strain and after cessation ofsteady shear flow.The Giesekus model gives slightly better predictions for steady shear flow and forthese stress relaxations, but fundamentally the Giesekus and Leonov models cannot be accepted asexact models for stress relaxation. On the other hand, the Larson model can describe both stressrelaxations well, but it gives too strong shear rate dependences for viscosity and coefficient of firstnormal stress difference. It is concluded that further studies on stress dependent model of eitherintegral or differential type will yield fruitful development of constitutive equations.

Pages 218-226


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Rheology of colloidal suspensions flocculated by polymerbridging

Yasufumi Otsubo

Department of Image Science, Faculty ofEngineering, Chiba University,Yayoi-cho 1-33, Inage-ku, Chiba-shi 263, Japan

Synopsis

When a high-molecular-weight polymer chain adsorbs onto more than two particles and causesflocculation in colloidal suspensions, the effect is referred to as bridging flocculation. Thesuspensions flocculated by polymer bridging show unique rheological behavior due to long-rangeinteraction and flexibility of bridges. The mechanisms of unique rheological behavior are discussedin relation to the bridging conformation. The suspensions respond elastically to small deformationwhen both the particle and polymer concentrations are increased above some critical levels.Although the elasticity arises only from the attractive forces between particles, thethree-dimensional network structure must be developed over the system for elastic responses ofsuspensions. The network formation process is analyzed on the basis of site-bond percolation.Scaling arguments enable us to show a power law dependence of elasticity on the difference ofprobability from the critical value. For site percolation process, the critical site probability andscaling exponent are independent of bridging conformation. However, the scaling analysis is notapplicable to the bond process, because a collection of particles connected by one polymer chainmay behave as a unit floc and a series of bridges in the floc cannot be broken to noninteracting

bonds.

Pages 227-232


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