A series of different substituted ureas were evaluated as latent accelerators in the curing of dicyandiamide-cured epoxy resin by DSC

TBA and rotation viscometer techniques. Experimental work revealed that the accelerating effect of the substituted ureas was promoted with the decrease of the magnitude of the a substituents

whereas the nature of the substitu-tents on the β and γ locations has no disturbance on the accelerating level. Comparis on of varionus ureas shows 4

4'-bi(N

N-dimethyl) urea diphenyl methane and 2

4-bi(N

N-dime-thyl) urea toluene to be the most effective among the accelerators evaluated in this work.The temperature required for cure completion of dicyanidimide-cured bisphenol A epoxy resin was decreased from 170℃ to 130℃ using these optimized accelerators. The storage life of epoxy formulation with 3phr accelerators at 30℃ might be delayed to over three months based on the extrapolation from Arrhenius plots and viscosity-storage time curves.