Spinodal demixing

Figure 12-12. Spinodal demixing in the system Co2Ti04-CoAl204 at T = 973 K for 2 days. Bright field TEM A = 5.5 nm [N. Burkert, et al. (1992)].

Spinodal demixing was excluded as a possible mechanism of phase separation during polymerization in solutions containing less than 12% rubber by volume [250]. 

Vycor and Pyrex are sodium borosilicate glasses in which use is made of spinodal demixing in the glass phase to provide strong resistance against chemical... 

The amplitude of small fluctuations in the local concenuation increases in time as shown schematically in figure III - 26. In this way a lacy structure of a membrane is obtained, and the type of demixing observed is called spinodal demixing [23]. 

Figure III 26. Spinodal demixing increase in amplitude with increasing...

The outer contours of the subsolidus curves delineating the metastable immis-cibility regions in Figure 3.20 correspond to the strain-free solvus or binodal (soUd lines), the inner contours (dashed lines) to the spinodal. A brief introduction to the theory of spinodal demixing of crystals is provided in Appendix D. 

The reaction-induced phase separation may also be described using conversion, x, versus composition, ( )m, transformation diagrams at a constant cure temperature (Fig. 8.5). Cloud point and spinodal curves bound stable, metastable, and unstable regions. Experimental studies of phase separation (Chen et al., 1993 Girard-Reydet et al, 1998), revealed that compositions located close to the critical point (e.g., trajectory 2 in Fig. 8.5) undergo spinodal demixing, while off-critical compositions (e.g., trajectories 1 and 3) exhibit phase separation by a nucleation-growth mechanism. 

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