Quenching from isotropic state

As a result of the strong drive to equilibrium, it is usually difficult to quench the isotropic melt to an amorphous glass when liquid crystal formation is possible. Extraordinary quenching techniques may be needed. Once produced, the amorphous state loses its metastability on heating above the glass transition Tga. The melt is quite unstable, so that it may not be possible to keep the melt from changing to the mesophase 21. ... 

The time-dependent rheological properties of disordered smectics are also peculiar. Figure 10-37 shows apparent G and G" data (labeled MD ) measured for 8CB after a quench from the isotropic state. Quenched samples contain a very high density of smectic defects, which produce elastic-like behavior in G at low frequencies of oscillation. The apparent moduli G and G" in Fig. 10-37 are not true linear viscoelastic moduli, since they were... 

A homogeneous mixture quenched from a stable phase into a thermodynamically unstable state within a phase diagram develops into an inhomogeneous system. Spinodal decomposition (SD) is induced by the instability of an order parameter, which is usually concentration [101]. In the early stages, the SD is interpreted within the framework of the Cahn theory for an isotropic SD [102,103]. In contrast, in the late stages, the SD is governed by diffusion or hydrodynamic processes and exhibits slow coarsening [104]. There are two types of order parameters that describe a system. One is a conserved order parameter such as concentration of binary mixtures. The other is a non-conserved order parameter such as the polarization of a ferroelectric... 

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