Predicting the phase behaviour of solvent-modified epoxy resins

Abstract

 The Flory–Huggins equation has been used to model the equilibrium phase behaviour of a solvent-modified epoxy resin intended for the fabrication of porous components by chemically induced phase separation followed by evacuation of the solvent after curing. Points in composition–temperature space corresponding to a transition from homogeneous to heterogeneous postcuring microstructures have been identified for a variety of solvents using a thermal gradient oven. Assuming this transition to coincide with the cloud-point curve corresponding to the gel point of the resin, the data were used in conjunction with the predictions of the Flory–Huggins equation to estimate the interaction parameter and its temperature dependence for each solvent. Phase diagrams in composition–conversion space were then calculated for a range of curing temperatures.