An investigation of the factors influencing the degree of exfoliation of an organically modified clay in a series of epoxy resins is reported. The use of sonication, choice of curing agent, effect of the moisture content of the clay, and the cure temperature were examined. The dispersion was characterized using a combination of rheological measurements, X-ray diffraction, and dynamic mechanical thermal analysis. R eological analysis of the clay dispersion in the epoxy monomer indicated that at high clay loads Herschel-Bulkley type behavior is followed. Higher cure temperatures and higher levels of clay moisture were found to influence the extent of exfoliation. Improvements in physical properties were observed through the addition of nanocomposites. The DGEBA/DDM and DEGEBA/DDS exhibited 2 and 4 degrees C increase, respectively, in T-g per wt % of added clay. DGEBF showed virtually no enhancement. (c) 2007 Wiley Periodicals, Inc.