The present work explores the characteristic rheological behaviors of polystyrene (PS) and poly(methyl methacrylate) (PMMA) melts in the startup shear. Through a detailed analysis of the stress overshoot, unexpected non-universal features are observed as follows. For all the examined melts, with increasing shear rate, the peak shear stress increases and the peak time decreases. The peak stress and the peak time exhibit a power-law relation, for which the scaling exponent is −1/2 for PS when the applied shear rate is larger than the reciprocal of the terminal time. Meanwhile, for PMMA melts, three scaling regimes with the exponent of −1, −1/4, and −1/2 are evident with the increase of the applied shear rate. Consequently, the relation between the peak shear stress and the peak time is not universal and chemistry dependent, even if the stress and the time are normalized by the plateau modulus and the Rouse relaxation time. This non-universality can be found in the literature data for the other entangled polymers.

The termination electrodes of chip passive components are mainly formed with dip coating processes of electro-conductive pastes. In this report, we had controlled the rheological properties such as viscoelastic and thixotropic properties of electro-conductive paste by changing mixing ratio of two polymer additives. Dip coating tests, including dipping and blotting processes, were conducted with a hand-made dip coat simulator and model inductor chips. Deformation behavior of the pastes in the processes and the final shapes were pictured and thickness of the electrodes were measured. It is considered that bulk flow of the pastes in the processes would be controlled with property measured under relatively large stress applied, like a shear viscosity. Even if the properties under the large stress conditions were same, the final shapes of the electrodes were different due to the another property defined under small stress conditions, namely, leveling behaviors were affected with the thixotropic properties of the pastes. Control of such kind of properties is important to obtain optimum electrode shapes.

The flow behavior of three types of surfactant solution (namely, Lipoquad C-50, Lipothoquad O/12, and cetyltrimethylammonium bromide [CTAB] with an NaSal counterion) passing through a slit was investigated by means of birefringence correlated with the degree of micelle orientation. With Lipoquad C-50, a high birefringence appeared in the slit section and upstream. With Lipothoquad O/12, the birefringence was low. With CTAB, the birefringence varied considerably with elapsed time. Different experimental results were thus obtained depending on the type of surfactant solution. To discuss the experimental results in depth, concentrations of 0.1× and 10× (2×) were used. With 0.1× concentration of all surfactant solutions, no birefringence appeared. With 10× concentration of Lipoquad C-50, there was no sign of the birefringence that was present with 1× concentration. With 10× concentration of Lipothoquad O/12, a birefringence was present that was not present with 1× concentration, and the distribution of the birefringence was almost the same as that with 1× concentration of Lipoquad C-50. The case with 2× concentration of CTAB was similar to that with 1× concentration. Moreover, the aforementioned results depended on the slit width or contraction ratio. To organize the experimental results systematically,the degree of spatial constraint (DSC) was defined, corresponding to the number of micelles occupying a unit volume. The DSC estimations showed that the birefringence appeared only when the DSC was between 5.9 × 10⁻⁶ and 1.2 × 10⁻⁵ mol (Lipoquad C-50 and Lipothoquad O/12) and between 1.8 × 10⁻⁶ and 7.3 × 10⁻⁶ mol (CTAB). Thus, the flow-induced structure generated by flow through an abrupt contraction and expansion was found to depend on a certain degree of micelle constraint.

The Weissenberg number, defined as the product of relaxation time and strain rate, reflects the ratio of elastic forces to viscous forces in a viscoelastic flow. Thus, at high strain rate based on a small (micrometer-scale) characteristic length,elastic properties are important for understanding the flow properties of dilute (100 ppm and 10 ppm) and ultra-dilute (1 ppm) aqueous polymer solutions. However, the very small elasticity and high strain rate make it difficult to measure the elastic properties precisely. In this study, flow properties and elastic stresses were investigated for dilute and ultra-dilute polymer solutions flowing through small slits with characteristic lengths of between 122 µm and 1.1 mm. The pressure drop (PD) and jet thrust (JT) for polyethylene oxide (PEO) and polyacrylamide (PAA) solutions were measured from their flow properties and elastic stresses, respectively. The pressure difference upon passing through a small slit and the momentum issuing from the slit at a constant flow rate were measured as the PD and JT, respectively. Although the measured PD of water and silicone oil agreed with the numerical predictions of the Navier–Stokes equation, the resultant PDs for all PEO samples were less than those for water and silicone oil. Similar results were obtained for all PAA samples; the PDs for aqueous solutions of 100 ppm, 10 ppm, and 1 ppm PAA were reduced. The JT values were also smaller than those for water and silicone oil. Even though ultra-dilute solutions were used, it is interesting that the PDs and JTs were reduced. Furthermore, to understand the experimental results, elastic stress was determined from the JT. The calculated elastic stress depended on the mean velocity. The relationship between the flow properties and the elastic properties was clarified, and the effect of surface tension was described by estimating the capillary number.