APPLICATION OF THE CAHN-HILLIARD EQUATION TO MISCIBLE SYSTEMS

The paper reconciles established theories of non-linear diffusion and flows driven by surface tension with recently resurrected approaches based on the Korteweg stress. Results are presented for the dissolution of particles initially created by spinodal decomposition but which are subsequently heated into a region of miscibility. The resulting non-linear diffusion and concentration-driven flows are simulated for a two-dimensiona l system using zero (lux and no slip boundary conditions at the walls. The dissolution dynamics were studied for a miscible polymer blend on length scales that were reasonably large multiples of the polymer radius of gyration, RG, and on time scales that were reasonable large multiples of the characteristic diffusion time, /?£ ID. As in spinodal decomposition, hydrodynamics are most important when the structure is cocontinuous and become relatively unimportant for paniculate blends. The general approach appears useful for a broad class of problems that involve mixing, unmixing, and phase transformations regardless of miscibility.