Conformational deformation of linear polymers in injection-molded parts

Conformational deformation of linear polymers in injectionmolded partsMasahiko Okumura and Mitsuru Nagasawa

Citation: Journal of Rheology (1978-present) 37, 564 (1993); doi: 10.1122/1.550426 View online: http://dx.doi.org/10.1122/1.550426 View Table of Contents: http://scitation.aip.org/content/sor/journal/jor2/37/3?ver=pdfcov Published by the The Society of Rheology Articles you may be interested in Surface-patterned micromechanical elements by polymer injection molding with hybrid molds J. Vac. Sci. Technol. B 31, 06FD01 (2013); 10.1116/1.4821649 Nanometer-size anisotropy of injection-molded polymer micro-cantilever arrays J. Appl. Phys. 111, 103530 (2012); 10.1063/1.4720942 Injectionmolded 13 piezocomposite sensor development: The last ten years J. Acoust. Soc. Am. 117, 2446 (2005); 10.1121/1.4786977 Photorefractive polymer composites fabricated by injection molding Appl. Phys. Lett. 80, 1156 (2002); 10.1063/1.1451990 Prediction of mechanical properties for injectionmolded parts of glassfiberreinforced nylon J. Rheol. 37, 551 (1993); 10.1122/1.550412

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Abstracts of manuscripts appearing inNihon Rheoroji Gakkaishi

(Journal of the Society of Rheology, Japan)Volume 20, 1992

547


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548 JAPANESE ABSTRACTS

Rheology of the yielding in polymer glasses

Yukuo Nanzai

Department of Mechanical Engineering, Osaka City University,Sumiyoshi-ku, Osaka 558, Japan

Synopsis

Post-yield plateau of a true-stress versus strain relation for glassy polymethyl methacrylate(PMMA) is illustrated to be a state of steady flow. A novel rate analysis applied to this steadyflow provided a unique functional relation between the activation energy IlH and the activationentropy t:J.S. This functional relation for the PMMA glass is demonstrated to agree with afunction of t:J.H vs t:J.S obtained from the relaxation data for the melt of the same PMMAsample. This agreement was also confirmed for polyvinyl chloride, polycarbonate, andpolystyrene, thus giving direct evidence verifying a change of the metastable glassy structureinto a liquid-like structure in the polymer glasses. Hence, the yielding in the polymer glasses isconvincingly concluded to be a transition phenomenon due to this structural change.


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JAPANESE ABSTRACTS 549

A study on pigment dispersing resins-The effect of resinsterminated with carboxyl groups

Toshikatsu Kobayashi

Research Center, Nippon Paint Co., Ltd., 19-17, Ikeda Naka, Neyagawa,Osaka 572, Japan

Shouji Ikeda and Kunihiro Osaki

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

Synopsis

Pigment dispersibility was studied for resins with various numbers of carboxyl groups at thechain end. The resins were synthesized by ring-opening polymerization of e-carprolactone.G-type resin had a carboxyl group at one end of each molecule. S-type resin was a mixture ofmolecules with 0, 1, or 2 carboxyl groups at the end of molecules. P-type resin was atetrafunctional resin terminated with carboxyl groups. L-type resin was without carboxylgroups. Dispersed pastes of Cu-phthalocyanine blue using G-type resin revealed a higher degreeof dispersion and a lower structural viscosity than pastes using S-type resin. Ti02 dispersedpastes were prepared using mixtures of G-type resin and L-type resin at various mixing ratios.As the amount of G-type resin increased, the degree of dispersion was enhanced and the yieldvalue decreased. L-type resin showed almost no effect on the yield values of TiO dispersedpastes. Ti02 dispersed pastes using P-type resin showed a lower degree of dispersion and ahigher structural viscosity than those using G-type resin. The resin molecules with no carboxylgroups did not affect the dispersibility or the structural viscosity of pigment dispersed pastes.The resin molecule with more than two carboxyl groups built up a structure among pigmentparticles and caused aggregation.


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Diffusion of PS in PS-PVME mixtures

Norio Nemoto

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

Takeshi Yamamura

Plastics Processing Lab., Mitsui Toatsu Chemicals Inc., 2-1, Tango-dori,Minami-hu, Nagoya 457, Japan

Kunihiro Osaki

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

Synopsis

Viscoelastic and forced Rayleigh scattering measurements were made on mixtures of PS andPVME over the wide range of temperature and PS molecular weight. The temperaturedependence of the tracer diffusion coefficient D of PS in PVME was well described by the shiftfactor aT obtained from time-temperature superposition of the dynamic shear modulus data ofPVME in bulk. The dependence of D on PS molecular weight was described by the free-drainingRouse chain model in the low M region where the coil size of the diffusing PS chain is smallerthan the mesh size of the PVME entanglement network. In the high M region, on the otherhand, D did not decrease in proportion to M- 2, being in disagreement with the prediction of thereptation model, but took a constant value nearly equal to the calculated D, value of the PVMEmolecule in bulk at the high M end. Two conjectures were proposed for interpretation of theabove anomalous diffusion behavior.


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Prediction of mechanical properties for injection-moldedparts of glass-tiber-reinforced nylon

Yoshinori Inoue, Takaaki Matsuoka, and Hideroh Takahashi

Toyota Central Research & Development Laboratories, Inc., 41-1, AzaYokomichi, Oaza Nagakute, Nagakute-cho, Aichi-gun, Aichi, 480

11, Japan

Synopsis

In injection-molded parts made of fiber reinforced thermoplastics, large warpages are frequentlyobserved. The warpage is caused by anisotropic mechanical properties yielded by fiberorientations in molded parts. Therefore, it is necessary to predict fiber orientations andanisotropic mechanical properties for estimating the occurrence of warpages. A computerprogram for evaluating fiber orientation in molded parts was developed by using Folgar andTucker's planar orientation model that was considered as fiber-tiber interactions. The classicallaminated plate theory was applied to predict mechanical properties (elastic modulus andthermal expansion coefficient) of molded parts in this study. The mechanical properties werepredicted in the analysis from calculated fiber orientations and mechanical properties of the fiberand the polymer. Predicted elastic modulus and thermal expansion coefficient were comparedwith measured ones for a molded plate of glass-tiber-reinforced nylon-6,6 (tiber content 30wt. %) to verify computational method. Predicted results agreed with measured ones very wellfor both the elastic modulus and the thermal expansion coefficient.


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Effect of exercise on mechanical properties and densityof bone

Yoshio Shirasaki and Tetsuya Tateishi

Mechanical Engineering Laboratory, Namiki-I, Tsukuba, Ibaraki 305,Japan

Yutaka Miyanaga

Department of Sports Medicine, University of Tsukuba, Tennodai 1-1,Tsukuba, Ibaraki 305, Japan

Synopsis

Effects of swimming and running trainings on mechanical properties of bone and bone densitywere investigated. Mechanical tests were conducted for tibial bone. The dynamic stiffness andtan 8 were measured by a viscoelastic spectrometer. The three-point bending test was performedwith an Instron-type universal testing machine. Bone mineral content was measured by photonabsorptimetry at the middle site of the tibial bone. In the swimming case the stiffness and tan {j

were, in average, larger for the trained rats than for the controlled group. The strength and thebone density were also larger for the trained group. In the running case, the negative effects wereobserved on these variables.


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JAPANESE ABSTRACTS

Electrorheological properties of suspensions ofsemiconducting particles

Yasufumi Otsubo

553

Department ofImage Science, Faculty ofEngineering, Chiba University,Yayoi-cho 1-33, Chiba 260, Japan

Masahiro Sekinea)

Colloid Research Institute, Ogura 350-1, Yahatahigashi-ku, Kitakyushu805, Japan

Synopsis

Semiconducting tin dioxide particles were covered with insulating layer and its effect onelectrorheological (ER) properties of the suspensions was examined under oscillatory andsteady shear. When the particles were coated with titanium dioxide by hydrolyzing titaniumtetraisopropoxide and heat-treated at 600 'C, the suspension in a silicone oil showed a high yieldstress at an electric field of 2.0 kV mm- t . However, since the titanium dioxide layer wassemiconducting, the current density was about 0.2 rnA cm- 2 and would not be applicable topractical device. Using aluminium ion, the titanium dioxide can be doped from a semiconducting to an insulating state. The particles covered with surface layer consisting of titanium dioxideand aluminum oxide provided excellent ER fluids in water-free systems. The coating of semiconducting particles by hydrolysis of alkoxides is very useful for surface modification of particles to improve the ER performance of suspensions.

a)Present address: Plastic Technical Center, Nippon Steel Chemical Co., Ltd., Ida 1618, Nakahara-ku,Kawasaki 211, Japan.


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Numerical analysis of electrorheological effect

Satoru Yamamoto, Takaaki Matsuoka, Hideroh Takahashi, and ToshioKurauchi

Toyota Central Research & Development Laboratories, Inc., 41-1,Aza Yokomichi, Oaza Nagakute, Nagakute-cho, Aichi-gun,

Aichi 480-11, Japan

Synopsis

The electrorheological effect found for the suspensions was numerically analyzed by three- andtwo-dimensional molecular-dynamics-Iike simulations. The shear stress in a uniform shear flowfield was calculated from results obtained by the simulations. The calculation suggested that theincrease in the apparent viscosity of the suspension might be attributed to the clustering of thedispersing spherical particles between a pair of electrodes under the influence of the appliedelectric field. The electrorheological effect calculated for the three-dimensional model wascomparable to that computed for the two-dimensional model. Both three- and two-dimensionalsimulations predict that the electrorheological fluid behaves as a Bingham fluid.

Properties of electrorheological 8uid containing sulfonatedpoly(styrene-co-divinyl benzene) particles

Yoshinobu Asako, Izuho Okada, Minoru Aoki, Satoru Ono, and MinoruKobayashi

Tsukuba Research Laboratory, Nippon Shokubai Co., Ltd., 1-25-12,Kannondai, Tsukuba 305, Japan

Synopsis

Two series of sulfonated poly(styrene-co-divinyl benzene)s (SSDs), different in degree ofsulfonation and in average particle size, were synthesized. The electrorheological behavior of thesuspensions of these SSDs dispersed in silicone oil was investigated. Shear stress induced byapplication of an electric field increased with increase in the degree of sulfonation and also inparticle size. The sedimentation velocity of these suspensions increased monotonically with thedegree of sulfonation and the average particle size. Another series of sulfonatedpoly(styrene-co-divinyl benzene), which had sulfonated surface layer and unsulfonated core,(SSDH), was separately prepared. Suspensions of SSDH showed electrorheological effectsimilar to those of SSD. The use of SSDH improved the stability of the suspension.


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Electrorheological effect of modified conductive particle/dielectric fluid system

Akio Inoue, Syunji Maniwa, and Tomio Satoh

Central Laboratory, Asahi Chemical Industry, Co" Ltd., 2-1 Samejima,Fuji, Shizuoka, Japan

Synopsis

Electrorheological (ER) effect of dispersions of anhydrous spherical particles with conductivepolymer core and nonconductive thin skin formed by chemical treatment was investigated indielectric fluids. The ER effect was also studied to particles of aluminum for comparison. It wasfound that shear stress enhancement of both samples depended on what types of methods wereused for observation of the ER effect. The ER effect of these dispersions was stronger under acthan dc electric fields in the rotary method, but stronger under dc than ac fields in the vibrationmethod. This is in clear distinction from the behavior of traditional ER ftuids containinghydrous particles, in which the ER effect is substantially the same under either ac or de fieldsin both methods, and is tentatively related to the shear employed in the measurements.

Transient stress response of ER suspension

Katsufumi Tanaka, Kiyohito Koyama, and Tamotsu Yoshida

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

Synopsis

Stress response of an ionic exchange resin suspension was measured by two types of stimulus; astep electric field in a steady shear flow and sinusoidal strain with various amplitudes under deelectric fields. It was found that the stress response to a step electric field of 1.38 kVfmm in asteady shear flow of 2.3 s-1 was composed of plural modes that took place in succession. Thesemodes were assigned to fast and slow modes with response time of 7 and 100 ms, respectively.Also, it was found that sinusoidal wave forms of the stress response to the sinusoidal strain of0.5 Hz in the de electric fields up to 2 kVfmm changed to nonsinusoidal ones with yield stressabove critical amplitudes of strain.


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Shear stress and aggregation kinetics of electrorheologicalfluids under alternating electric fields

Howard See and Masao Doi

Department ofApplied Physics, Nagoya University, Chikusa-ku, Nagoya464-01, Japan

Synopsis

The effectof periodic ac and pulse electric fields on the shear stress of an electrorheological fluidis investigated by computer simulations. It is observed that as the frequency of the applied field(OJ) is increased under a constant rate of shear (r), the shear stress passes through a minimum.It is found that there is a distinct difference in the aggregation processes due to the inducedelectric dipoles at frequencies above and below this critical frequency; for low frequencies theclustering follows the electric field variation, while at high frequencies the clusters are unable tocompletely break up. These considerations of the clustering process lead us to propose a scalinglaw for the shear stress: uxy=uxy(OJ/y). This result agrees with experiments and with computersimulations.

Electrorheological effects of suspensions consistingof poly-p-phenylene particles and silicone oil

Tohru Shiga, Megumi Fujimoto, Yoshiharu Hirose, Akane Okada,and Toshio Kurauchi

Toyota Central Research & Development Labs. Inc., Nagakute-cho, Aichigun 480-11, Japan

Synopsis

The electrorheological (ER) effects of suspensions of poly-p-phenylene (PPP) particlesdispersed in a silicone oil were studied experimentally. The experimental results were analyzedqualitatively using a model in which the particles act as points dipoles in electric fields and thenformed many chains due to dipole-dipole interactions at a short range. Large ER effect has beenobserved in the suspension by using the PPP particles with small amount of adsorbed CuCI2.

The magnitude of the ER effect could be controlled by the content of CuCI2. The suspensionshowed the high temperature working limit of at least 100 "C, The effects of particle concentration, field intensity, and particle dielectric constant on the ER effect were not qualitativelysimilar to the model. It was found that the increase of the real part of the complex dielectricconstant of the PPP particles at lower frequencies played an important role in producing the EReffect.


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Electrorheological properties of suspensions containingnonaqueous additives under high temperature

condition

Takahisa Akatsuka, Ryoichi Yoshimura, and Jiro Toyama

Research and Development Department, Nippon Mektron, Ltd., Kukizakimachi, Inashiki-gun, Ibaraki 300-12, Japan

Synopsis

The electrorheological (ER) properties of cellulose suspensions which include nonaqueouspolar materials as active additives for ER effect were studied comparing with water-activatedsuspension. The nonaqueous polar materials are alcohols, amides, and amines from theviewpoints of dielectric constant and vapor pressure. The ER properties of these suspensionswere measured with a cylindrical rheometer at temperatures up to 120'C. Also storage stabilityat 120°C was investigated. The nonaqueous additives were effective to activate cellulosesuspension: Especially at higher temperatures, the nonaqueous additives were more effectivethan water was. The shear stress of the water-activated ER fluid decreased as the temperatureincreased. On the contrary the shear stress of the ER fluids, which contain the nonaqueousadditives, increased as the temperature increased. and became greater than that of thewater-activated ER fluid at room temperature. Furthermore the nonaqueous additives hadadvantages of decreasing the electric power consumption and of improving thermal stability ofshear stress after the storage for 250 h at 120°C.


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Cluster formation in electrorheological fluids: Theoryand computer simulation

Jun-ichi Takimoto

Scientific Research Laboratory, Nissan Motor Co., Ltd., 1, Natsushimacho, Yokosuka 237, Japan

Synopsis

It is well known that dispersed particles in electrorheological fluid (ERF) form chain-likeclusters under an electric field. Many authors consider this cluster formation to be the origin ofthe electrically induced shear stress Te• If the shear rate r is increased, however, the clustersshould be broken into shorter segments. Is this consistent with the experimental fact that Te isroughly independent of y? To answer this question, we have studied the cluster formation undershear flow by simple theory and computer simulation, which are based on the force balancebetween the hydrodynamic resistance and electrostatic attraction among particles. The resultsshow that, when r is increased, the length of clusters becomes shorter in proportion to r- 1I2,

while the stress due to the clusters remains roughly constant. This indicates that the clusters areindeed the origin of the induced stress.


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JAPANESE ABSTRACTS

Spinning rheology (2)-Analysis of melt spinningbehaviors and its application

Hideaki Ishihara, Seishu Hayashi, and Hiroshi Yasuda

Katata Research Center, Toyobo Co., Ltd., 2-1-1 Katata, Otsu,Shiga 520-02, Japan

Synopsis

559

There are many rheological problems in the melt spinning process. They can be classified intotwo categories, i.e., the problems in shearing flow and those in extensional flow. The former isconcerned with extrusion of molten PET (polyethyleneterephthalate) through spinneretorifices.Bagley's plots showing the relationship of pressure drop to L/D of orifice were done toobtain the end correlation in the capillary flow of PET. By using this end correction values, therelaxation time of molten PETwas estimated to be around 2 X 10- 3 S under some assumptions.With regard to the problems in the extensional flow three typical and important examples wereshown from both experimental and theoretical aspects. (I) Fine denier filament spinning forobtaining fibers with less than about 10 /lm in diameter is a challengeable theme in the meaningof a conflict with extensional flow instability, so called draw resonance phenomenon. To solvethis difficulty, it can be suggested that optimal spinneret orifice design will be required forinstance. (2) High speed spinning is a process of stress-induced crystallization of PET. Dependence of spinning behaviors such as neck-like deformation and mechanical/structural propertieson PETmolecular weight was investigated. Crystallization of higher molecular weight PETwasfound to occur at lower spinning speed compared with that of lower one. (3) Air jet meltspinning for multifilament system was investigated both theoretically and experimentally. Computation results showed a good agreement with experimental ones in terms of the stretchingspeed in ejector. Birefringence values of as-spun fibers can be estimated by using computedoutputs.


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Spinning rheology (3)-Dry spinning behavior andcharacteristics of the polyurethane elastic fibers

Hideaki Ishihara, Tetsuo Kotani, and Seishu Hayashi

Katata Research Center, Toyobo Co., Ltd., 2-1-1 Katata, Otsu,Shiga 520-02, Japan

Synopsis

Dry spinning behavior of the segmented polyurethane-urea elastometer/solvent binary systemwas studied theoretically and experimentally. Computer simulation was carried out by solvingthe partial differential equations numerically for discussing the structure and properties ofas-spun fibers. Spinning stress computed at the take-up point was found to be useful fordescribing the segmental orientations and the aggregate structure of the hard segment in relationto the mechanical properties such as e1astomeric character of the fibers. With increase of thespinning stress, orientation of the hard segment becomes higher. Orientation of the soft segment,however, is almost random regardless of spinning stress, resulting in the origin of thee1astomericcharacter. Dependence of the spinning stress on the hydrogen bond concentration ofurea group suggested that the aggregate structure of the hard segment was smaller when thefiber was spun at a higher spinning stress.


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JAPANESE ABSTRACTS

Flow behavior of oil-in-water emulsions

Yasufumi Otsubo

561

Department of Image Science, Faculty ofEngineering, Chiba University,Yayoi-cho 1-33, Chiba-shi 260, Japan

Robert K. Prud'homme

Department of Chemical Engineering, Princeton University, Princeton,New Jersey 08544

Synopsis

The flow behavior of oil-in-water emulsions is examined as a function of the volume fraction ofdispersed drops, drop size, and viscosity ratio of internal to external phases. The results areinterpreted in terms of internal circulation, deformation, and breakup of drops. At low volumefractions, the viscosity decreases with increasing shear rate and becomes constant at high shearrates. The Newtonian viscosity is independent of drop size. The viscosity in the pseudoplasticregion increases with decreasing drop size. A change in drop size at constant volume fractioncauses a horizontal shift in the viscosity versus shear rate curve. As the viscosity ratio decreases,the relative viscosity at a given volume fraction is reduced because hydrodynamic forces causeinternal circulation which reduces the velocity perturbations outside drops. At high volumefractions where a network of thin liquid films is formed, the change in drop size leads to avertical shift of the viscosity curve. The flow behavior in highly concentrated emulsions isgoverned by total interfacial area. When the deformation and breakup of drops occur at a highshear rates, the emulsions show pseudoplastic flow.


07:45:31


Mechanical properties of natural rubber compositesreinforced with cellulose fibers

Shoichiro Yano

Industrial Products Research Institute, 1-1-4 Higashi, Tsukuba-ehi,Ibaraki30~ Japan

Bengt Stenberg and Per Flink

Royal Institute of Technology, Department of Polymer Technology, S-10044, Stockholm, Sweden

Synopsis

The mechanical properties of natural rubber composites filled with cellulose short fibers wereinvestigated with respect to fiber concentration and fiber orientation. Strong anisotropy causedby the fiber orientation was observed in the mechanical properties at high fiber loading. Theultimate tensile strength in the longitudinal direction to the fiber orientation had a minimum atVr'" 12.5%, while the transverse strength decreased with Vf values. The logarithmic elongationat break decreased linearly with Vf' and the transverse elongation was higher than the longitudinal elongation. The modulus of the composite increased with fiber concentration, withsemiempirical equation E=kl{ 1+[Vml( 1- ~5)11 being valid for the transverse direction andthe longitudinal direction at lower fiber loading. The longitudinal modulus was much higherthan the transverse modulus. In order to improve adhesion between the fibers and matrix,polyallylacrylate was grafted on cellulose fibers, but grafting was ineffective on the mechanicalproperties of the composite. The dynamic viscoelastic properties of the natural rubber compositewere also investigated. The dynamic modulus, E', increased with increasing amounts of fiberconcentration above the glass transition temperature. The loss modulus, E", had a peak at about-36 ·C; which shifted to higher temperatures with increasing amounts of mixed fibers. Theactivation energy for glass transition of the composites was calculated at 198.6-228.6 kl/rnol,depending on fiber concentration for the longitudinal direction. The dynamic viscoelasticity inthe transverse direction to the fiber orientation was not affected by filled fibers and the activationenergy was 187.3 kllmol, approximately the same value as for the unfilled rubber vulcanizate.


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JAPANESE ABSTRACTS

Uniaxial and biaxial elongational flow of low densitypolyethylene/polystyrene blends

Takaaki Hattori

563

Nippon Petrochemicals Co., Ltd., 3-2, Yako-2, Kawasaki-ku, Kawasaki210, Japan

Toshikazu Takigawa and Toshiro Masuda

Research Center for Biomedical Engineering, Kyoto University, Shogoin,Sakyo-ku, Kyoto 606, Japan

Synopsis

Uniaxial and biaxial elongational flow behavior of low density polyethylene (LOPE)/polystyrene (PS) blends (LOPE/PS=2!l) with and without 5 wt. %styrene-ethylene-propylene block copolymer (SEP) was studied. In these blends, LOPE was thematrix phase and PS was the dispersed phase. Measurements of the uniaxial elongationalviscosity 7/+(t,E) and the biaxial elongational viscosity 7/P (t,E) were made using a Meissnertype uniaxial elongational rheometer and a lubricated-squeezing-type equibiaxial rheometer,respectively. In the linear region, the relation between the transient shear viscosity 7/ + (t) andthe transient elongational viscosity, which were predicted by three-dimensional linear Maxwellmodel, i.e., E£ (t) =37/+ (t) and 7/jj (I) =67/+ (I), did not hold well. This may be attributed toa volumetric resistance against the deformation perpendicular to the elongational directionbecause of the existence ofPS particles. In the long-time region, a difference of 17£ (I,E) betweenblends with and without SEP was observed. In the case of uniaxial elongational flow, it may bepresumed that a contribution of the deformation of PS domains to the elongational flow behavior has to be taken into account when the elongational strain is large.


07:45:31


Conformational deformation of linear polymers ininjection-molded parts

Masahiko Okumura and Mitsuru Nagasawa

Toyota Technological Institute, Tempaku-ku, Nagoya 468, Japan

Synopsis

The birefringence in injection molds of noncrystalline linear polymers arises from two differentkinds of deformation; one incorporated with the change of intersegmental distance and one withthe deformation of molecular conformation. Their contributions to birefringence wereseparately observed in injection-molded polystyrene. The birefringence originating from themolecular-conformational deformation was compared with computer simulation results, inwhich the rheology constitutive equation of Leonov was employed to calculate the shear and thenormal stresses.

Viscoelastic properties of star poly(vinyl ether)

Hirotsugu Yoshida, Hajime Shohi, and Yoichi Mikami

Corporate Research Institute, Sekisui Chemical Co., Ltd., 2-1 HyakuyamaShimamoto-cho, Mishima-gun, Osaka 618, Japan

Synopsis

Viscoelastic properties of novel three-arm star poly(isobutyl vinyl ether) (PIBVE) wereinvestigated and compared with those of linear PIBVE. In a high molecular weight (M) region,the zero-shear viscosity 110 increased with M more rapidly for three-arm star PIBVE than forlinear PIBVE. The steady-state compliance ./1, tended to increase with M for three-arm starPIBVE, but appeared to be independent of M for linear PIBVE. These linear viscoelasticfeatures of three-arm star PIBVE are qualitatively the same as those for other star polymersinvestigated so far. In a nonlinear viscoelastic regime, the Cox-Merz rule held for both threearm star and linear PIBVEs. In a vicinity of an onset of decrease in the shear viscosity 1/ withshear rate r, relations between the reduced viscosity 1//1/0 and the reduced shear rate Y./1,1/oagreed fairly well for three-arm star and linear PIBVE samples examined.


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JAPANESE ABSTRACTS

Application of rheology to polymer technology

Kazuhiko Ninomiya

565

WWF Japan, Nissei-Akabanebashi, Building 3-1-14 Shiba, Minato-ku,Tokyo, Japan

Synopsis

A research project undertaken during the period of 1960-1969 by the "Bussei Group" of JapanSynthetic Rubber Co. was reviewed,and the prologue and the epilogue for this long term projectwas presented. The overall framework was first shown as the target system of the project whichaimed in correlating the quality of rubber products with the molecular characteristics of rawrubbers. Eight principal research areas were then identified to develop the subsystems whichconstitute the total system. For each of the research areas, a general way of approach to therheological problems was shown and then some typical examples of the results thus obtainedwere illustrated. Finally, in the prologue, a review of the historical background of this researchproject was given, and in the epilogue, the reason by which this project had to come to an endwas examined from a managerial point of view.

Rheological studies on the pipeline transportation of coalslurries and oil

Hiromoto Usui

Department of Chemical Engineering, Yamaguchi University,Ube 755, Japan

Synopsis

Drag reduction caused by the injection of polymer solution into a turbulent pipe flow wasinvestigated by means of a flow visualization technique. Turbulent fluctuating velocity in adrag-reducing flow was determined by a tracer method. It became evident from theexperimental results that the defect of Reynolds stress existed over the wide range of the radialposition in a polymer drag-reducing pipe flow. The optimum preparation method of coal watermixtures (CMW) has been developed. The present study contributed to the successfulproduction of highly loaded CMW with lower viscosity. An evaluation method of the dynamicstability during the transportation of CWM was proposed. This method was based on athixotropy model for slurries, and it was successfullyused for the estimation of dynamic stabilityof CWM with a laboratory stability test.


07:45:31


Slit flow characteristics of rigid PVC measured by slit dies

Jun-ichi Okamoto and Akira Ishibashi

YKK Kurobe Factory Research & Development Division, 200 Yoshida,Kurobe, Toyama 938, Japan

Synopsis

The slip velocity of molten rigid PVC was investigated. Using Mooney's method, slip velocitywas obtained from flow curves which were measured by slit dies with different thicknesses.When surface roughness of dies was 0.1 pm, the slip velocity logarithmically increased withshear stress. When an extrusion temperature was 180 ·C, the slip flow was dominant and theratio of slip velocity to mean velocity was about 90%. Its ratio decreased with increasingextrusion temperature. The slip velocity rapidly decreased when the surface roughness wasincreased from 2 to 10 pm. Over 10 pm of the roughness the apparent slip velocity became zero.Therefore the thickness of the slip layer was supposed to be within several microns.

Numerical simulation of contraction flow for viscoelasticfluids at high Weissenberg number by the streamline

upwind finite element method

Yoshifumi Kuwano, Toshihisa Kajjwara, and Kazumori Funatsu

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

Synopsis

Numerical simulation of viscoelastic flow at high Weissenberg number (We) was carried out bythe streamline-upwind finite element method with the subelements for stress componentsproposed by Marchal and Crochet. This method and the Galerkin finite element method wereapplied to the stick-slip flow with the singular point in order to examine the effectiveness of thismethod. The OIdroyd-B model was used as a constitutive equation. This model incorporatesstrong elasticity and numerical solutions sometimes diverge. When the Galerkin finite elementmethod was used, the numerical solutions had oscillation and the loss of convergence occurredat a relatively low value of We. On the other hand, when the streamline-upwind method wasused with the stress subelements, the oscillation of numerical solutions did not appear and thesolution could be obtained up to a high value of We. Using the latter method, the calculation ofthe tapered contraction flow was carried out with the Giesekus model as a constitutive equation.The limit values of We were not encountered and we could calculate even at We> 100 usingvarious values of model parameters. It was concluded that the streamline-upwind finite elementmethod with the stress subelements was very useful to simulate the contraction flow up to highvalues of We.


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JAPANESE ABSTRACTS

Erythrocyte sedimentation phenomena I: Tilt angledependence of upflow velocity in inclined vessel

Yoshiharu Toyama, Atsuko Idonuma, Toshiaki Dobashi,and Akio Sakanishi

Department of Biological and Chemical Engineering, Faculty ofEngineering, Gunma University, Kiryu, Gunma 376, Japan

Synopsis

567

In order to clarify the relation between the enhanced erythrocyte sedimentation rate in aninclined vessel and the medium upflow underneath the downward-facing wall of the vessel, wehave measured the upflow velocity V along the vessel length y and the width {) of the upftowlayer at tilt angles 8 of 10', 20', 40", and 60°, Sample was a swine erythrocyte suspension atnonaggregated state at the volume fraction of 0.2. Polystyrene latex particles with I-J.Lmdiameter were mixed in the suspension to visualize the motion in the upftow layer. Observationswere made with a video system under an invert microscope at room temperature. The upftowlayer began to be formed immediately after the sample injection, and reached to the steady statewithin 10 min, while keeping a thin layer. The time for reaching the steady state decreased withincreasing 8. The upftow velocity was much higher by two to three orders of magnitude than thesedimentation rate. Both V and {) increased with increasing 8. The observed velocity profileswere represented by the reduced equation 1- VIVmax= (l-xI8)2 as predicted by the Acrivosand Herbolzheimer theory. Here, x is a coordinate taken along the end line at the bottom of thevessel.


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Measurement of the second normal stress difference ofaqueous polymer solutions and an aqueous

detergent solution by utilizing a flow induced by thegravity between two parallel plates

Tatsuo Sekino

Graduate School ofScience and Technology, Niigata University, 2-no-cho,Ikarashi, Niigata, Japan

Tomiichi Hasegawa

Faculty of Engineering, Niigata University, 2-no-cho, Ikarashi, Niigata,Japan

Hiroaki Kobayasi

Radio Application Division, NEC Corporation, 1-10, Nisshin-cho, Fuchu,Tokyo, Japan

Synopsis

The second normal stress is measured for aqueous solutions of Separan with polymer weightfraction from 1% to 3% and for 10-2 mollt aqueous cetyltrimethylammonium bromide(CTAB) solution containing 1.5X 10-2 mollt of sodium salicylate (NaSal) as an added salt.The measuring device is a newly developed one composed of two parallel plates vertically setand opened to the atmosphere at the sides, and the solution is made to flow down through theslit between the two parallel plates by the gravity. The torque on one of the plates induced bythe flow is measured and the second normal stress difference is estimated. The second normalstress differenceobtained is negative for Separan solutions, and its absolute value is found to be

of the same magnitude as the shear stress. For the CTAB:NaSal aqueous solution, the secondnormal stress difference is negative and the magnitude is larger than the values for Separansolutions. Its absolute value is I%-10% of the first normal stress difference.


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Viscoelastic properties of poly(ethylene terephthalate)melts

Naoyuki Matsuo and Yoshitaka Ishimuro

Material Characterization Laboratory, Toray Research Center, Inc., 3-3-7,Sonoyama, Otsu, Shiga 520, Japan

Synopsis

This paper describes a detailed study on effects of moisture and solid phase polymerization onmelt viscoelastic properties of poly(ethylene terephthalate) (PET). We found a dryingcondition and an experimental procedure which did not induce any variation of either molecularweight or molecular weight distribution in samples during periods of sample preparation and ashort time run of viscoelastic measurements. For a long time run, 7]' and G' increased with timeand especially the increase of the latter was remarkable. The similar behavior was observed fornylon-66 but not for poly(butylene terephthalate) (PBT). It is suggested that highly branchedand/or cross-linked substances were produced in the samples besides linearly polymerized ones.

Characteristic time for self-diffusion coefficient of linearpolymers in semidilute solutions

Yoshiaki Takahashi, Masayoshi Yamaguchi, and Ichiro Noda

Department ofApplied Chemistry, Nagoya University, Chikusa-ku,Nagoya 464-01, Japan

Synopsis

The concentration dependence of characteristic time r; for self-diffusion coefficient D, of linearpolymers in good solvents was discussed in comparison with that of the weight average relaxation time T w for viscoelastic properties. Similarities were found for the concentration regions ofT r and t:w' and also for the concentration dependences of r's in the respective regions. On thebasis of the similarities, it is pointed out that almost all the D, data of polymers at finiteconcentrations so far published should not be discussed in terms of the reptation model since thesolutions are not regarded as those in the well entangled regions.


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Membership inThe Society of Rheology

Any bona fide physical scientist or engineer with an interest in the deformation orflow of matter is invited to join The Society of Rheology. Although there are no statedminimum academic requirements for membership, the nature of our discipline is suchthat the rewards of membership accrue in direct proportion to one's involvement inthe technical side of rheology. We welcome practitioners of rheology, worldwide.Application may be made to the Chairman of the Membership Committee:

Professor A. Jeffrey GiacominRheology Research LaboratoryMechanical Engineering DepartmentTexas A & M UniversityCollege Station, Texas 77843-3123FAX: (409) 845-3081EMAIL: [email protected]

The Journal of Rheology is mailed free to members.


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Documents

Conformational deformation of linear polymers in injection-molded parts