Morphological, thermal, rheological, and mechanical properties of reactive compatabilized blends of poly(butylene terephthalate) (PBT) and Polyamide-6 (PA) containing EGMA copolymer were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), advanced rheometric expansion system (ARES), and universal testing machine (UTM). From the results of thermal analysis by DSC, the melting point of the 30/70 PBT-PA blend was broadened after EGMA was added in the blends, since the enthalpy of melting of the PBT-PA somewhat decreased with the increase of EGMA content. From this result, it is suggested that the EGMA affected to the crystallization behavior and crystallinity of the PBT-PA blends. From SEM micrographs of the 70/30, 50/50, and 30/70 PBT-PA blends, the droplet size of the 30/70 PBT-PA blend was about 0.8 ${\mu}{\textrm}{m}$ which was smaller than that of the 50/50 and 70/30 PBT-PA blends. The complex viscosity of the 30/70 PBT-PA blend observed to be higher than that of the 50/50 and 70/30 PBT-PA blends. From the results of the morphology and rheological properties for the PBT-PA blends, it is suggested that the compatibility is increased in the 30/70 PBT-PA blend than the 50/50 and 70/30 PBT-PA blends. From the results of mechanical properties, it was found that the tensile strength of the 30/70 PBT-PA blend increased with the increase of EGMA up to 2 phr, while tensile strength of the blend in which EGMA content was higher than 2 phr decreased with the increase of EGMA content. From the results of morphological, thermal, rheological, and mechanical properties for the PBT-PA-EGMA blends, it is suggested that the EGMA could be used as a compatibilization role in the blends.

As part of continuing efforts to investigate nonlinear dynamics and stability of film casting process, our earlier results obtained by Lee et al. (2001b) have been extended in the present study to cover the film casting of both extension thickening and extension thinning fluids. The same instability mechanism and draw resonance criterion previously derived have been found valid here, and a rather complex dynamic behavior of film width in contrast to that of film thickness has also been confirmed. The effect of fluid viscoelasticity on draw resonance, however, exhibits opposite results depending on whether the fluid is extension thickening or thinning, i.e., it stabilizes film casting in the former while destabilizing in the latter. The encapsulation extrusion method which recently has been successfully employed to stabilize industrially important paper coating process, has been theoretically explained in the present study as to why such stabilization is possible.

The phase morphology is an important factor in the rheology of immiscible polymer blends. Through its size and shape, the interface between the two phases determines how the components and the interface itself will contribute to the global stresses. Rheological measurements have been used successfully in the past to probe the morphological changes in model blends, particularly for dilute systems. For more concentrated blends only a limited amount of systematic rheological data is available. Here, viscosities and first normal stress differences are presented for a system with nearly Newtonian components, the whole concentration range is covered. The constituent polymers are PDMS and PIB, their viscosity ratio can be changed by varying the temperature. The data reported here have been obtained at 287 K where the viscosities of the two components are identical. By means of relaxation experiments the measured stresses are decomposed into component and interfacial contributions. The concentration dependence is quite different for the two types of contribution. Except for the component contributions to the shear stresses there is no clear indication of the phase inversion. Plotting either the interfacial shear or normal stresses as a function of composition produces in some cases two maxima. The relaxation times of these stresses display a similar concentration dependence. Although the components have the same viscosity, the stress-component curves are not symmetrical with respect to the 50/50 blend. A slight elasticity of one of the components seems to be the cause of this effect. The data for the more concentrated blends at higher shear rates are associated with a fibrillar morphology.

We reported on the eletrorheological (ER) properties of several semiconducting polymers including poly (p-phenylene) (PPP), poly (acene quinone) radicals (PAQRs), microencapsulated polyaniline (MPANI) and polyaniline (PANI) those we synthesized. The yield stress dependence on electric field strength for the ER fluids using these semiconducting polymers was mainly examined. The yield stress, which is an important design parameter for ER fluids, was observed to satisfy a universal scaling function, allowing that yield stress data for all the ER fluids examined in this study collapse onto a single curve for a broad range of electric field strengths. The proposed scaling function incorporates both the polarization and conductivity models.

This review article summarizes results of recent viscoelastic and dielectric studies for entangled cis-polyisoprene (PI) chains. The PI chains have the so-called type-A dipoles parallel along the chain backbone, and their slow viscoelastic and dielectric relaxation processes reflect the same global chain motion. However, this motion is differently averaged in the viscoelastic and dielectric properties, the former representing the isochronal orientational anisotropy of individual entanglement segments while the latter detecting the orientational correlation of the segments at two separate times (0 and t). On the basis of this difference, the viscoelastic and dielectric data of the entangled PI chains were compared to elucidate detailed features of the chain dynamics. Specifically, the molecular picture of dynamic tube dilation (DTD) incorporated in recent models was tested for linear and star PI chain. The comparison revealed that the DTD picture was valid for linear PI chains but failed for the star PI chains in the dominant part of the terminal relaxation. The failure for the star chains was related to the pre-requisite for the DTD process, rapid equilibration of successive entanglement segments through their constraint release (CR) motion: For the star chains, the dilated tube diameter expected in the terminal regime was considerably large because of a broad distribution of motional modes of the chains, so that the CR-equilibration required for DTD could not occur in time. The terminal relaxation of the star chain appeared to occur through the CR process before the expected DTD process was completed. The situation was different for the linear chain exhibiting narrowly distributed motional modes. The dilated tube expected for the linear chain was rather thin and the required CR-equilibration occurred in time, resulting in the success of the DTD picture. These detailed features of the chain dynamics was revealed only when the viscoelastic and dielectric properties were compared, demonstrating the importance of this comparison.