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Development spinodal structure

TEM can also be used to follow the development of structural features during spinodal decomposition [131] and reaction-induced phase separation [1]. [Pg.177]

In polymeric materials, the morphology development upon spinodal decomposition proceeds through various stages [92,93]. In the early stage of decomposition a co-continuous structure develops. A dispersed two-phase structure results only in the late stage of phase separation and the shape of the domains is not uniform. The morphology development upon spinodal decomposition is presented in Fig. 6. [Pg.181]

The spinodal pattern completely disappears in the area where the material was heated by the laser beam beyond Tc. After the laser is switched off, this circular pattern again survives for a long time (Fig. 18B, C) before a somewhat irregular structure develops in this area. It slowly grows in diameter (Fig. 18C) and moves away from the central spot like a spherical wave. [Pg.177]

The simulation result for the time evolution of structure factors as a function of the scattering vector q for an A/B 75/25 (v/v) binary blend is shown in Fig. 9 where time elapses in order of Fig. 9c to 9a. The structure factor S(q,t) develops a peak shortly after the onset of phase separation, and thereafter the intensity of the peak Smax increases with time while the peak position qmax shifts toward smaller values with the phase-separation time. This behavior suggests that the phase separation proceeds with evolution of periodic concentration fluctuation due to the spinodal decomposition and its coarsening processes occurring in the later stage of phase separation. These results, consistent with those observed in real polymer mixtures, indicate that the simulation model can reasonably describe the phase separation process of real systems. [Pg.21]

For the better understanding of blend morphologies, the fundamental mechanisms of morphology development are discussed, viz. the liquid-solid phase transition (crystallization), the liquid-liquid phase separation e.g., spinodal decomposition under non-isoquench depth), as well as the complex mechanism of the morphology generation that results from the competition between these two transitions. The effects of chemical reactions and flow fields on morphology development have also been discussed. Finally, several evidences of a local structure in single-phase polymer-polymer mixtures are presented. [Pg.547]

A more sophisticated DIA was proposed for the studies of sphemlite formation and phase separation in polymer blends [Tanaka, 1986 Tanaka and Nishi, 1987]. With a different computer vision, shape features of phase-separated structure was obtained [Gur et al., 1989]. The digitalization gives the possibility of two-dimensional Fourier transformation. A power spectrum of the two-dimensional Fourier transformation was given for the structure developed by spinodal decomposition [Tanaka et al., 1986]. In the real space, one cannot see the order in the image clearly, whereas the characteristic wavelength and the distribution can be seen in the reciprocal space representation. [Pg.556]

Another type of morphology development was reported for PP/EPR blends [Inaba et al., 1986]. High molecular weight blends of PP and EPR are immiscible. One-phase blends were prepared by precipitation from a solution. This mixture underwent phase separation via spinodal decomposition (SD), followed by crystallization. However, in this case the spherulites were formed seemingly ignoring the bi-continuous SD-structure. [Pg.560]

Various terms are u in the literature for the development of a network structure ageing, annealing and maturation. In many cases network formation is clearly time dependent. In other cases network formation seems to be instantaneous and a time dependence cannot be observed. In physical networks this may be the result of a sudden temperature decrease, resulting in a spinodal phase separation. During network formation the increase in the storage modulus may be of the order of 10 or more. It is clear that a horizontal plateau... [Pg.249]


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See also in sourсe #XX -- [ Pg.206 , Pg.210 ]




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