We investigated the strong thermal adhesive properties between thermoplastic polyamide elastomers (PAE) and polyimide (PI) films. Three kinds of PI films (UPILEX ^® S film, UPILEX ^® RN film and Kapton^® film) were used in this study. From the analysis by the Young-Düpre theory with the PI film surface observations, the surface tensions of PI films and the contact angles of PAE melts on PI films, it was found that the interfacial tension between PAE and PI film is considerably small. The excellent thermal adhesive properties between the PAE and PI films are thought to be due to the low interfacial tension between these polymers and the thick interfacial thickness. However, in order to obtain sufficient adhesive strength, it is important to set the preparation conditions so that the interface thickness formed by both polymers is sufficiently thick. The thermal adhesive mechanism of the PAE/PI film obtained in this study is similar to that between PAE and thermoplastic polyurethane or crosslinked polybutadiene.

Microporous films were obtained from an extruded sheet of isotactic polypropylene (PP) containing N,N’-dicyclohexyl-2,6-naphthalene dicarboxamide as a crystal nucleating agent under suitable hot-stretching conditions. The crystalline structure before and after the stretching operations was evaluated by two-dimensional wide-angle X-ray diffraction, and it was found that the original sheet contains a large amount of β-form crystals oriented to the transversal direction (TD) by the extrusion at 200 °C, which is lower than the dissolution temperature of the nucleating agent in PP. During stretching of the sheet, α-form crystals oriented to the stretching direction appeared by the transformation from β- to α-form crystals. Moreover, numerous microvoids were generated by stretching around at 100 °C to the machine or flow direction (MD) of the sheet, although the microvoids were prolonged. The sequential TD stretching, however, expanded the area of voids, leading to a microporous film with a pronounced porosity.

In this study, we investigated the relationship between the amorphous structural changes associated with enthalpy relaxation and the Heat distortion temperature (HDT) in polystyrene injection moldings.
It was clarified that the longer heat treatment time, the more enthalpy relaxation progressed. Also, an extrapolation glass transition temperature (T_ig) increased by heat treatment. In addition, long-time heat treatment caused the high-temperature shift of the storage modulus (E') decrease temperature near glass transition temperature (T_g). Since the increase in T_ig and the high-temperature shift of E' decrease temperature correlated with the enthalpy relaxation, they can be closely related to the enthalpy relaxation. Thus, we considered that the segment motion of polymer chain was suppressed as the enthalpy relaxation progressed.
At long-term heat treatment, the enthalpy relaxation and the HDT were correlated. Furthermore, density increased by the heat treatment, and the increase in density also correlated with the progress of the enthalpy relaxation. Therefore, we considered that the polymer chains densely packed along with the enthalpy relaxation. As the result of polymer chains being densely packed, the segment motion of polymer chains near T_g can be suppressed and the HDT increased.

Liquid crystalline (LC) phase behavior, higer-order structure, and mobility of mesogenic groups were investigated by using DSC, polarizing optical microscopy, small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD) and dielectric relaxation spectroscopy (DRS) for random copolymers composed of cyanobiphenyl-based side-chain LC and the amorphous components with various compositions.
LC phase behavior of the copolymers was systematically changed depending on the mole fraction of the LC component, f_LC11. When f_LC11 > 0.75, incorporation of small fraction of the amorphous component resulted in slightly highered LC order and almost unchanged LC-isotropic transition temperature, T_iso. This may be because the copolymerization of the amorphous component canceled the inherent frustration in the LC homopolymer, which comes from the dissidence between lateral distance of adjacent nearest mesogenic groups in the smectic LC phase and that of the side-chains on main-chain.
According to the DRS measurements, incorporation of the amorphous component also accelerated the molecular mobility of the mesogenic groups, which may be also related to the relaxation of the internal conformational frustration because of the dissidence.

An analysis model for the transient viscoelastic flow in the film blowing process was newly developed based on the Galerkin finite element method and incorporating the cooling and crystallization behaviors. Assuming that physical quantities such as temperature and stress are constant in the thickness direction, the process was approximated to be one dimensional in the axisymmetric coordinate system, and the Lagrangian analysis, which involves remeshing and rezoning, was performed. In calculating the air pressure difference, constant air mass in the bubble was assumed and the effect of opening angle of the guide rolls, which lead the blown bubble to the pinch roll, was investigated. The viscoelastic properties were expressed by the multi-mode PTT model. Regarding crystallization characteristics, a phenomenological crystallization model developed by us was used. The model was based on the non-isothermal crystallization characteristics evaluated using a high-speed DSC. Four types of polyethylene, i.e. two LLDPEs, a blend of LLDPE and LDPE, and HDPE, were used and a comparative study of experimental results and results of model analyses for the film blowing process was carried out. Guidelines for appropriate input parameter settings such as the negligibility of the parameter for orientation induced crystallization and the necessity of adopting the heat transfer coefficient functions were obtained. By reflecting these findings in the simulation, the experimental results of polyethylene film blowing, including the unstable film formation behavior, could be predicted well by the developed model.

Emulsified particles of O/W type emulsions using alkyl-type-associative water-soluble polymers were minimized and viscosity- and elasticity-increase occurred by adding a small amount of lipophilic surfactant. Rheology measurements of the emulsions were performed, and the emulsification states were considered. Physical cross-linking is thought to be made through the interaction between the hydrophobic moieties in polymer and the lipophilic surfactants at the surface of emulsified droplets. This network structure holds emulsified particles in fine states preventing from phase inversion and separation.

The viscoelastic properties of entangled DNA solutions covering the loosely to the tightly entangled region were investigated. Dynamic birefringence measurements found that the stress-optical rule held for the solutions with c < 15 mg/ mL while above this concentration, the rule did not. This result indicates that the curvature mode contributes to the rubbery plateau modulus at high concentrations, which is characteristic of a tightly entangled system where the entanglement length becomes smaller than the Kuhn length. The nonlinear viscoelasticity of the tightly entangled system was also discussed. In the loosely entangled region, the steady-state viscosity follows the Cox-Merz rule. In contrast, the shear rate dependence of the steady-state viscosity became more significant in the tightly entangled region, and the nonlinearity increased with increasing concentration. Stress overshoot was commonly observed in the viscosity growth function at high shear rates. The maximum strain, γ_m, determined from the shear stress maximum, was observed at γ_m = 2 in the loosely entangled system, according to the behavior of ordinary flexible polymers. On the other hand, in the tightly entangled region, γ_m became smaller as the concentration increased.

We hypothesized that the shear-induced structure, SIS, of wormlike micelles solutions could be suppressed by increasing the volume concentration of micelles, because emergence of spatial heterogeneity in the micellar concentration is not induced. In order to prove this hypothesis, we prepared samples with high concentrations of surfactants and counterions, keeping their molar concentration ratios constant, and observed the occurrence of SIS. The occurrence of extremely large stress overshoot in the step shear test was used as a criterion for the occurrence of SIS. We found disappearance of the SIS by increasing the micellar concentration in all the molar ratio. Although it is known that the relaxation time of the micellar solution decreases with the increase in the surfactant molar concentration, the absence of the SIS at high surfactant molar concentration is not attributed to the reduction of the relaxation time because the SIS can be found even when the temperature is increased. The relaxation time was not the dominant factor in SIS, but the spatial movement of micelles was a necessary condition for the generation of SIS. In addition, the effective body integrability of wormlike micelles was calculated and compared with the experimental results to determine the critical effective body integrability for SIS generation.

The dominant responsible factor for the disappearance of shear-induced structure, SIS, in aqueous wormlike micelle solutions is examined. It has been reported that the of SIS is accompanied by a spatial distribution of micelle concentration as the micelle structure changes, which generates on a much larger scale than the size of the micelles. Therefore, the time required for the heterogeneity caused by the SIS formation to be completely eliminated was determined by a continuous step shear test with a constant interval time. The time required for the stress behavior in the second step to completely match that in the first step was defined as the SIS disappearance time. The SIS disappearance time evaluated in this experiment is 3.7 times longer than the relaxation time for micelle entanglement, regardless of the molar concentration ratio, and can be predicted by a simple relaxation curve. The critical conditions for the onset of SIS in the start-up behavior of accelerated shear flow, in which the rheological properties are determined by the balance between the formation and disappearance of SIS, were determined, and it was shown that the maximum value of viscosity normalized by zero shear viscosity can be characterized by the product of the rate of increase of shear rate and the square of the SIS structure disappearance time. It was confirmed that the SIS resolution time is one of the important rheological properties in the SIS formation state.

Rouse model is the basic molecular model for unentangled linear polymer chains in melts. Recent studies suggest that the Rouse parameters characterizing the unentangled melts, the spring strength κ , the segmental friction coefficient ζ, and the mean-square Brownian force intensity B, change under fast flow thereby providing significant rheological nonlinearities with those melts (Matsumiya et al., Macromolecules, 51, 9710 (2018)). This article theoretically analyzes effects of the flow-induced changes of these parameters on the dielectric and diffusion behavior of the Rouse chain having so-called type-A dipoles parallel along the chain backbone. It turned out that the dielectric behavior under steady shear is determined by non-equilibrium parameters, r_κ = κ/κ_eq and r_ζ,ij= ζ_ij/ζ_eq but irrelevant to r_B,ij = B _ij/B_eq, where the subscript “eq” stands for the quantities at equilibrium and the subscripts “ij” denote the spatial direction under shear flow: i and/or j = x, y, and z for the velocity, velocity gradient, and vorticity directions, respectively. Specifically, the complex dielectric permittivity ε* is analytically expressed in terms of the parameters r_κ and r_ζ,ij, which in turn enables us to evaluate these parameters from data of the dielectric relaxation time and intensity under steady shear (obtained in future experiments). In contrast, the advective diffusion behavior under steady shear is determined by r_ζ,ijand r_B,ij but irrelevant to r_κ. The mean-square displacement ‹Δr²_CM› of the center of mass defined with respect to the known non-diffusive advection point is analytically expressed in terms of r_ζ,ijand r_B,ij, thereby allowing us to evaluate r_B,ij from the diffusion data under steady shear and the dielectrically determined r_ζ,ij. The method of experimental evaluation of the non-equilibrium parameters presented in this article provides us with a complementary basis for analyzing nonlinear rheological behavior of unentangled melts.