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We report a new synthetic method to construct supramolecular A8Bn (n=1, 2, 4) miktoarm star copolymers by host‐guest complexation between a resorcinarene‐based coordination capsule possessing eight polystyrene chains and 4,4‐diacetoxybiphenyl guest molecules that retain one, two or four polymethyl acrylate chains. The formation of the supramolecular A8Bn (n=1, 2, 4) miktoarm star copolymers was confirmed by dynamic light scattering (DLS), size‐exclusion chromatography (SEC), and diffusion‐ordered NMR spectroscopy (DOSY). Differential scanning calorimetry (DSC) measurements revealed that the miktoarm copolymers were phase‐separated in the bulk. The micro‐Brownian motion of the A8B4 structure was markedly enhanced in the bulk due to a weak segregation interaction between the immiscible arms. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of rheological behavior on dynamics of bubble coalescence. In situ observations on polymers with different rheological behaviors were conducted to study coalescence dynamics. Four patterns of interface deformation were observed. Deformation during coalescence was analyzed by applying image-processing schemes and rheological models to the in situ observations. Polymer with Newtonian behavior showed nucleation and coalescence of spherical bubbles that created a planar interface. The planar interface was deformed by a combination of biaxial and planar elongational flows. Coalescence in polymers with non-Newtonian behavior is characterized by penetration with a parabolic shaped interface. The deformation of parabolic interface was due to biaxial elongational flow. However, the interface deformation of the polymer with cross-linked structure was due to an integration of biaxial and elongational flow. Further, cross-linking was also observed to have an effect on coalescence time. POLYM. ENG. SCI., 46:680-690, 2006. © 2006 Society of Plastics Engineers, INTRODUCTION Physical foaming with C[O.sub.2] has been attracting industrial attentions since the invention of microcellular plastics [1-3]. The process consists of four steps: (1) dissolution of physical foaming agent into [...]

Non-Newtonian and non-isothermal flow simulations based on 3-D FEM were applied to a special and conventional elements of a twin-screw extruder. The screw mixing element (SME), a kind of special element, was a distributive mixing promoter consisting of a standard screw profile with slots cut across the flight tip to increase leakage flow. The full flight screw (FF) and the kneading block (KB) were examined as conventional elements in order to contrast the mixing behavior with the SME. The accuracy of numerical results was verified by experimentally measuring pressure and temperature. Additionally, marker particle tracking analysis was carried out to evaluate the distributive and dispersive mixing. Using the above analyses, the following results were obtained: The pumping capability of the SME was smaller than that of the FF and was the same as for the KB. The SME suppressed heat generation and showed the lowest temperature distribution of the three elements. For distributive mixing, the SME showed the best pe rformance judging from the mixing coefficient G, residence time distribution, and area stretch distribution based on a laminar mixing mechanism. A higher rotational speed achieved better distributive mixing performance. For dispersive mixing defined by stress distribution, the SME showed the second best performance next to the KB. It also showed better dispersive mixing performance with increasing rotational speed. The SME had the advantages of low heat generation and good distributive mixing., 1. INTRODUCTION Twin-screw extruders (TSE) consist of many kinds of screw elements, which have a wide variety of characteristics. In recent years, several kinds of special elements have been proposed [...]

We have calculated and visualized numerically the mixing performances of four kinds of assemblies in twin-screw extruders that were composed of right-handed or left-handed double-flighted full flight screws and neutral or left-handed stagger angle kneading blocks, taking into consideration industrial usage. We have found that the mixing performance of a kneading block interposed between full flighted screws is strongly influenced by the flow of full flighted screws, in particular that of a neutral kneading block. Furthermore, we have proposed the simple mixing indices, which could describe both uniform mixing and heterogeneous mixing, and also applied them to our marker tracking results of four kinds of assemblies. We found that more uniform mixing is obtained for the assembly that has a neutral kneading block before the right-handed full flight screw, and a more enhanced heterogeneous mixing is obtained for the assembly that has a left-handed kneading block before the left-handed full flight screw. The reaso n for the latter mixing ability will relate to the quasi-channels of the left-handed kneading block, through which marker clusters flow while elongating., INTRODUCTION Twin screw extruders (TSEs) have been widely used for blending and pumping apparatuses in the polymer industry. By changes in their geometry and operating conditions, TSEs can be used [...]

We have developed a three-dimensional non-Newtonian and non-isothermal flow analysis of the twin screw extruder (TSE) using the finite element method. This code can simulate the fully filled parts of [...]

HARUHIKO WATANABE [*] KAZUMORI FUNATSU [**] Numerical simulations of double-layer flow from tube-in-orifice spinnerets have been carried out using a differential constitutive equation. The streamline-upwinding finite element method with 4 [...]

TAKESHI ISHIKAWA [1] KAZUMORI FUNATSU [*] Three-dimensional nonisothermal flow simulations in the kneading disc regions of co-rotating twin screw extruders were performed using a finite element method. The standard Galerkin [...]