lower curing temperature, slower chain diffusion, smaller hard phase Kinetic Control of Epoxy Resin Microstructure Elliot Douglas, Department of Materials Science and Engineering, University of Florida Epoxy resins have been shown to form a two phase microstructure of a highly cross-linked region (“hard phase”) embedded in a matrix of a lower crosslink density region (“soft phase”). Physical properties of epoxy resins, such as fracture toughness and diffusion coefficient of water in the epoxies, are expected to depend on this two phase morphology. Highly cross-linked hard phase Soft phase with a lower cross-linking density We believe the microstructure can be controlled kinetically by balancing the rate of the curing reaction (chain growth) and the nucleation and growth process of the hard phase (chain diffusion). Our experiments have already shown that microstructure greatly depends on curing temperature and curing reaction rate. The next goal is to develop a model to describe and predict the formation of this morphology. Off stoichiometry, slower reaction rate, slower chain growth, larger hard phase lower curing temperature, slower chain diffusion, smaller hard phase