Reaction systems where both reactants and products are in the liquid and solid phase (no vapor phase present) are being used commercially to produce high molecular weight monomers or intermediates used in the production of specialty and commodity polymers. Specific examples include bisphenol A, paradichloro-benzene and n-methyl phthalimide. Other classes of materials that must be processed in the melt include elemental and compound semi-conductors such as silicon and gallium arsenide, and superconducting materials such as barium/copper/yttrium/oxygen systems. One advantage of some of these two phase systems is that reaction and separation occur in the same unit, greatly reducing processing costs. The structure and properties of multicomponent solid-liquid phase diagrams play and important role in determining the behavior of these unit operations (also referred to as melt processing units). The PI plans to develop a broad comprehensive theory of multicomponent reactive solid-liquid phase diagrams that will produce practical rules for conceiving and designing melt processing systems. These systems have unusual phase equilibrium behavior when reactions are present, including the appearance of reactive azeotropes in ideal mixtures. These and other features normal azeotropes in non-ideal mixtures. These and other features of the equilibrium behavior influence what can and cannot be achieved in reaction-separation systems. The PI plans to use certain invariants from differential geometry to provide a complete classification of the phase behavior, and ultimately to predict it, from an incomplete knowledge of the equilibrium relations. The ultimate goal is to develop a broad fundamental understanding of reactive melt processing that will lead to useful guidelines for the synthesis and design of such systems.
