Evolution of phase separation

Figure 16.9 Optical micrographs obtained for a 50/50 sPP/EPDM blend isothermally quenched at 100°C. Left column depicts the evolution of phase separation under the unpolarized condition and right column indicates the growth of crystals under the cross-polarized condition.

However, as in this section the evolution of phase separation in the metastable region will be analyzed, conditions will be such that a fractionation of the oligomer species between the continuous and dispersed phases will be produced. Therefore the available statistical distributions are of no value and it is necessary to calculate the evolution of the oligomer distributions in both phases using the kinetic equations describing the polycondensation. 

The time evolution of phase separation by spinodal decomposition is described by a diffusion equation for the density (pure fluid) or species concentration (mixture) [101,103,105]. To illustrate the basic aspects of the theory, we consider the onedimensional, pure fluid case. Generalization to more dimensions, and extension to binary incompressible mixtures involve just a change of notation. For a pure fluid, the diffusion equation reads... 

Fig. 4.18 Time evolution of phase separation kinetics in the three-phase region as observed by Poon et al. [99]...

Time evolution of phase-separating morphology (or concentration fluctuations, in general) in binary mixtures has been extensively studied as a research theme on nonlinear and nonequilibrium phenomenon in various fields of science [1]. Especially, a lot of work has been devoted to the spinodal decomposition process (SD) [2], a phase-separation process for the mixtures with thermodynamic instability. Experimental studies, especially time-resolved... 

Figure 1S.8 Evolution of phase separation in a 128 x 128 x 128 three-dimensional domain without a patterned substrate, (a) Without elastic energy (b) With isotropic elastic energy.

Figure 1S.21 Evolution of phase separation, showing (a) PS (b) PAA and (c) solvent at different times for C3 = 0.60.

The ternary model was established to investigate the effects of a solvent in polymer blends during phase separation. In cases of constant solvent concentration it emerged that, the less solvent that was in solution, the slower was the evolution of the morphology in phase separation. This effect was due to the polymers being immiscible with each other, but both being miscible with the solvent. The addition of a solvent decreased the free energy level in the blend, which in turn slowed down the evolution of phase separation. The mechanism of phase separation with solvent evaporation was further complicated by dynamic solvent evaporation from the ternary system. 

Fig. 7.1 The evolution of phase separation morphology of NOA65/E7 under UV exposure for different duration of time, observed through a POM at a magnification of x200 (Deshmukh and Malik 2013b)...

Fig. 23a-d Time evolution of phase-separated structure at a t=2,846 min, b 1=4,310 min, c t=9,823 min, d 1=21,508 min. Solid part of each figure represents PB-rich phase. Bottom plane of each 3D image as shown hy gray edges represents glass surface. A part of the phase-separated structure in d was removed to show a cross section of 3D structure, demonstrating the formation of thick wetting layer and columnar structure . Bar corresponds to 50 pm... 

TDGL is a microscale method for simulating the structural evolution of phase-separation in polymer blends and block copolymers. It is based on the Cahn-Hilliard-Cook (CHC) nonlinear diffusion equation for a binary blend and falls under the more general phase-field and... 

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