Morphology of phases

The present study should be seen as a step in the evolution of the colloidal morphology of phase inversion membranes, which conceptually began with dense polymer films and diverged into the two principal branches skinned and skinless membranes (Figure 1). 

Figure I. Evolution of the colloidal morphology of phase inversion membranes...

This document is organized into three sections. The first defines terms basic to the description of polymer mixtures. The second defines terms commonly encountered in descriptions of phase-domain behaviour of polymer mixtures. The third defines terms commonly encountered in the descriptions of the morphologies of phase-separated polymer mixtures. 

Enhancement of mechanical properties is of interest only if it is not accompanied by a loss of other important properties of the blend. Of particular concern for such polymer blends is stiffness, because most means of increasing impact strength also reduce stiffness (14-19). But this is not the case for the iPS-fc-iPP-iPS-iPP blends studied here as seen in Table II. It is clear that the enhancement in toughness just described is not accompanied by a loss of stiffness, but it is essentially unaffected by the compatibilizer. And the stiffness of iPS-fc-iPP-iPS-iPP is higher than that of iPP and HIPS. The impact-modulus behavior seems to be due to the tough (or rigid) characteristics, morphologies of phases, and semicrystalline isotactic structure of each block in the iPS-b-iPP diblock copolymer. 

The phase behavior and morphology of phase-separated polymer blends play a vital role in the design of membrane transport properties (Robeson 2010). Numerous applications of polymeric membranes involving gas and liquids are known. Although different transport models have been utilized successfully to relate morphology with transport properties, there is enough room for improvements as membrane applications continue to grow in such areas as gas separation. 

Considering these equations one has to keep in mind that the morphology of phase-separated polymer systems is often mwe complex or even not well defined. This makes a quantitative modeling quite difficult. 

FTIR did not give any further information about the morphology of phase separation but from the absorption spectra it was possible to determine the concentration of the different forms of nitrogen in the bulk polymer (urethane, urea and amine nitrogen). 

Phase-Separated Networks. There are two basic morphologies of phase separation which could, at least in principle, produce a network structure. Firstly, a phase separation may occur which results in a localized polymer-rich region, possibly by a nucleation and growth process. This could act as a junction zone. The growth of this rich phase may be limited by geometric constraints, such as entanglements or the copolymeric nature of the molecule. Secondly, the polymer-rich phase may not be localized but form a continuous network. This is more likely to be the case when the nucleation density is high or when spinodal phase separation occurs. 

Wange R, Vogel J., Horn L., Holand W, and Vogel W., "The Morphology of Phase Formations in Phosphate Glass Ceramics," Silic. Ind., 231-36 (1990). 

Glotzer, S.C., DiMarzio, E.A., and Muthukumar, M. (1995) Reaction-controlled morphology of phase-separating mixtures. Phys. Rev. Lett., 74, 2034-2037. 

Motoyama, M. and Ohta, T. (1997) Morphology of phase separating binary mixtures with chemical reaction. J. Phys. Soc. Jpn., 66, 2715-2725. 

Another important, but rather apparent, difference between elastic and viscoelastic effect is the final (or very late-stage) morphology of phase separation An elastic effect affects the final morphology since it is an energetic effect. On the other hand, a viscoelastic effect does not affect the final morphology, which is purely determined by energetic factors such as interfacial energy, since there remain only viscous effects and no elastic effects for t X). 

The formation of phase-separated domains is identical to the development of interfaces between the conjugate phase domains. That is, the local morphology of phase-separating system may be affected by the presence of additional interfaces such as substrate surfaces and container walls. 

The solvent in the blends can increase the mobility of the polymer molecules and decrease the interaction force between the macromolecules. From Figure 15.18, it can be seen that the solvent in an immiscible polymer pair can decrease the free energy level of the system and increase the miscibility of the two polymers. Therefore, the solvent concentration can influence the resultant pattern in the spinodal decomposition indeed, the solvent concentration can be changed to investigate the influence of solvent composition on the morphology of phase separation. The morphology evolution of ternary systems with different solvent composition is shown in Figure 15.22 in this case the initial condition is the same. 

Polyblending offers the possibility of combining the best properties of both polymers in the blend, particularly in a two-phase system [1-4]. Thus, when gross phase separation causes incompatibility, it is highly desirable to reduce the size and morphology of phase separation, and in particular to strengthen the interface... 

To calculate morphologies of phase separation of PDLCs, many simulation methods have been developed [137]. Zhu et al. [138] have performed a Monte Carlo simulation to investigate the phase behaviors of PDLC by using the Lebwohl-Lasher model for nematogens [139]. One of the methods is to numerically solve the... 

Figure 7.3 Transient morphologies of phase-separating polymer blends with and without nanoparticles, (a) Optical micrograph of a phase-separating deuterated polystyrene (dPS)/polybutadiene (PB) 70 30 critical mixture after coarsening for 1510 min at 25 °C [40] (b) snapshot of a Langevin dynamic simulation ofa critical (50 50) AB-mixture, with...

Temperature distributions within the material are governed by the following characteristics density p, specific heat c, thermal conductivity X and thermal diffusivity a = Mp c. All these characteristics depend on the chemical composition of the refractories. Conductivity and diffusibihty also depend on mineralogy and morphology of phases. The stress fields resulting from thermal distribution and mechanical boundary conditions are governed by the thermal expansion and the behavioral laws. Thermal expansion depends on the chemical and crystallographic natiue of the material. 

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