The flow behavior of dispersed systems of flue cured tobacco powder and water in a ram-type extruder was investigated under various conditions of temperature, water contents and nozzle length. The tensile behavior of the extruded rod-shape dispersions were also examined, and the following results were obtained;
The pressure distribution in the nozzle in the direction of nozzle length was nearly linear, and the inclination of the pressure converged to a constant level near the nozzle exit. The flow was recognized to be a laminar flow in this part of the nozzle. The flow pattern of the system (42.9% in water contents) was a pseudoplastic flow under the condition of less than 4.5×10² sec^-1. At higher shear rates, a Newtonian flow pattern was likely to appear, though not ascertained by experiment. The relationship between apparent viscosity and shear rate was shown to be a straight line whose inclination was about -0.7 in logarithmic scales. Apparent viscosity increased with decrease of the shear rate.
The strain-stress curve showed that there was an elastic deformation at the early periods of tensiling of the extruded rod. On the other hand, the elastic energy given to the system at the nozzle entrance was carried by the elastic deformation of the system through the nozzle. Therefore, after a rod was shaped in the nozzle, the system could be replaced by the rod in elastic deformation. In this system the elastic energy was shown to be nearly proportional to the tensiling rate.

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Axial velocities were measured for the flow of viscoelastic fluids, 0.2% and 0.3% aqueous solutions of sodium polyacrylate and 0.3% aqueous solution of polyacrylamid, in the exit region of a cylindrical tube. Fluids were extruded through tubes of 1.98 cm and 3.00cm diameter into an open receiver tank filled by test fluids. The velocity was measured by photographing the locus of a tracer particle as a series of points on a 35mm film. Tracer particles were hydrogen bubbles of diameter less than 0.3mm generated periodically by electrolysis from a scratched enamel wire of diamter 0.3mm.
It was observed that the velocity profile was fully developed even in the cross section at one diameter upstream from the exit. It was also observed that for small values of N (defined by the ratio of the inertial force to the elastic force), the fluid elements near the tube wall decelerated as they approached to the exit, but those far from the tube wall accelerated and took maximum velocities near the exit. This behavior might be mainly due to the momentum exchange between the extruded fluid and surrounding. When N was larger than a certain value, a central core was observed where axial velocities maintained the fully developed values to the exit. This core spread to the tube wall with increasing N.
It may be concluded that the velocity profile at the exit is fully developed over the whole area of cross section except the very near region of the tube wall at sufficiently large values of N.

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In order to disclose the rheological characteristics of human articular cartilage, cancellous bone and those composite at knee joint, regional and directional differences of dynamic viscoelasticity and strength were investigated. All the specimens were obtained from normal knee joint at operation. In normal cancellous bones of tibial condyle at 45°flexion, the dynamic compressive elastic modulus was about 60kg/mm2 and the peak value of phase-lag was about 10 degrees. Comparison of these measurements with those of the femoral head and condyle, indicates that the larger dynamic elastic modulus and the lower degree of phase-lag of tibial condyle makes an adequate structural adaptation to dynamic weight-bearing. These facts indicate that the cartilage-cancellous bone composite tends to be ductile and effective as a shock-absorber. In a joint such as hip and knee, the obvious strength and stiffness difference between loaded and unloaded region would also indicate that cancellous bone responds to load by remodelling. Next, viscous and viscoelastic properties of 5 samples of synovial fluid obtained from 4 patients with arthritic knee joints has been studied by using a rheometer. The non-Newtonian behavior of the fluid has been confirmed and the viscosities were much lower than those of normal fluid, especially at the low shear rate region.

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The dynamic rigidity and loss modulus of blood were measured. Two different kinds of apparatus were used at different ranges of frequency and shear rate. For the blood sample with a 43 per cent hematocrit, the dynamic viscosities η′ and η″ decreased with increasing shear rate. At high shear rates, η″ was not observable. For a blood sample with a larger hematocrit, 64 per cent,η″became observable.
For horse blood samples with the hematocrit below 50 per cent, the dynamic rigidity and loss were found to be time dependent at low measuring frequency and shear strain. This would be associated with the formation of rouleaux and their network.

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An apparatus was devised to measure the rheological properties of foam from toilet soap. The principle of measurement was based on the analysis of oscillation damped by foam.
Measurements by this apparatus were conducted at approximately 2.5Hz on the soap foam obtained from a 5% (wt/wt) toilet soap aqueous solution at 40°C. The diameter of each bubble remained approximately 100μ, while the specific volume of foam varied much with varying condition of preparation.
The storage shear modulus increased from 500 fo 850 dyne/cm2 as the specific volume of foam increased from 10 to 25cm3/g. On the other hand, the dynamic viscosity was not much affected by specific volume and was approximately 15-20 poise. The loss tangent for the foam was calculated to be about 0.3.

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The effect of surface treatment of reinforcing fibers by nitric acid was studied in the light of the torsional and tensile dynamic mechanical properties of aromatic polypyromellitimide and polytrimellitamideimide reinforced by carbon fiber filaments. The surface treatment of fibers gave smaller temperature dependence of the storage rigidity modulus of composite materials at the softening temperature of the resin. Torsional measurements showed a mechanical absorption peak above its glass transition peak due to adsorbed layer characteristic of composite materials. The storage Young's modulus obtained by tensile oscillation measurements using a Rheovibron instrument showed no decrease at softening temperature of the resin. The reinforcing materials are shown to be effective on the elevation of mechanical thermal stability.

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The piezoelectric and elastic constants of bone were determined at 10Hz in the range of temperature from -50 to 150°C. The piezoelectric constant of dry bone was nearly independent of temperature. The piezoelectric constant of 7.4%hydrated bone was larger than that of dry bone at temperatures below 0°C, but smaller at temperatures above 0°C. Similarly, the elastic constant of hydrated bone was larger than that of dry bone at below -30°C, and smaller at above -30°C. A theoretical estimate of the piezoelectric constant of bone was made by using a parallel combination model of collagen fibers and hydroxyapatite crystals, which was in agreement with the observed value.

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The bulk modulus κ* of a dispersion of spherical particles having a shell structure is theoretically obtained as follows:
_??_
with
_??_
Here κ and μ, are the bulk modulus and the rigidity of the medium, respectively, and c is the volume concentration of particles. Each particle has the shell region with thickness a-a and stiffnesses C_γγγγ, C_γγθθ, C_θθθθ, C_θθΦΦ, and the inside region with bulk modulus κ′, where a′and a are the inner and outer radii of the shell. These parameters are related to K, M, A, x and y in the above expression for P as follows:
K=(1/3)(2C_γγγγ+C_γγγγx)
M=(1/4)(2C_γγθθ+C_γγγγy)
A=a′/a
x and y=_??_
where x refers to plus sign.

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The dependence of viscosity η on shear rate γ, ranged from lower Newtonian to upper Newtonian flow regions has been measured for solutions of a narrow distribution poly-styrene (M_w=3.92×10⁵, M_w/M_n=1.10) in diethyl phthalate at 30.0°C. Plots of (η-η_fric)/(η_o-η_frie) versus fγτ_R(η_o-ηfrie)/2η_o are accordant with the Graessley theoretical curve for the fluid of narrow distribution polymer, where η_o is the zero shear viscosity, η_fric is a frictional viscosity parameter nearly independent of shear rate, and τ_R=6η_oM/π²cRT. f is a shift factor which is 1 for the solutions of concentrations c from 0.562 to 0.0603g/cm3, and decreases with decreasing concentration below 0.0330g/cm3.
Results show that the steady shear viscosity consists of the shear dependent entanglement viscosity η_ent and the shear independent frictional viscosity η_fric and that the upper Newtonian behavior appears when η_ent becomes smaller than η_fric with increasing shear rate. A calculation of fractional reduction in the entanglement density under the existing shear condition shows that there remain residual entanglements even in the region of upper Newtonian flow.

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