The relationship between apparent elongational viscosity obtained by using a spinline rheometer and a variety of flow conditions in its measurement is investigated for a dilute polymer solution. The numerical calculations are carried out for a FENE-P dumbbell model and the experiments are performed for a 100 ppm aqueous solution of polyacrylamide.
Elongational rates and elongational stress are significantly changed along the spinline. The apparent elongational viscosity depends on the flow rate and the spinline length. It is found that this dependence of the apparent elongational viscosity is due to the effect of inertia. Finally, a comparison is made between the apparent elongational viscosity and the steady elongational viscosity.

View full abstract

Flow patterns and fiber orientation in the two-dimensional flow of fiber suspension through a contraction or an expansion are calculated numerically by the use of Dinh-Armstrong model. The assumption that fibers lie tangent to streamline is excluded from the present calculation. Therefore, the fiber orientation is obtained by integration of the Jeffery's equation along a streamline.
A vortex near the salient corner in the suspension flow is different from that of Newtonian fluid. The dependence of the vortex length on aspect ratio and volume fraction of fiber is discussed.
In the contraction flow, fibers lie tangent to a streamline in the main flow region, but not in the vortex region. In the expansion flow, however, fibers rotate along the streamline, hence fibers do not lie tangent to a streamline even in the main flow region. Furthermore, the application of stress relief mechanism is examined for the change of the vortex length.

View full abstract

In this study, we discuss the applicability of the Moiré method for measuring the mechanical deformation of textile end-use products. The results can be summarized as follows:
(1)The application of the Moiré method made it possible to describe the 2-dimensional deformation of the distance between adjacent loop centers and the skew angle of loops of knitted fabric at any point. The case of tensile stress on knitted cotton fabric was reported. (2)The Moiré method can thus be applied to detect the inhomogeneity ofloops and the skew angle, or the cover factor of knitted fabric. (3)The Moiré method will offer some suggestions for improving the production and construction of knitted fabric, when the measuring systemis improved to get higher precision and further 3-dimensional measuring is applied.

View full abstract