SYNOPSISThe morphology of a system consisting of a bisphenol A diglycidylether (DGEBA) based epoxy, cured with a cycloaliphatic diamine (4,4'-diamino-3,3'-dimethyldicyclohexylmethane, 3DCM) , in the presence of an epoxy-terminated butadiene-acrylonitrile random copolymer (ETBN), was studied as a function of the cure schedule and the initial rubber concentration. Scanning ( SEM) and transmission ( TEM ) electron microscopy, differential scanning calorimetry (DSC) and dynamic mechanical analysis were used to characterize the generated morphology. SEM results were not affected by the type of mechanical test and strain rate. Trends observed for the particle size distribution, the volume fraction of dispersed phase, the concentration of dispersed phase particles and the composition of both phases as a function of polymerization temperature and rubber concentration, were discussed. A correlation between the viscosity a t the cloud point and the average size of dispersed phase particles was found for different systems, independently of the cure temperature and the initial rubber amount.

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SYNOPSISThe mechanical properties of a system consisting of a bisphenol A diglycidylether (DGEBA) epoxy, cured with a cycloaliphatic diamine (4,4'-diamino-3,3 dimethyldicyclohexyl-methane, 3DCM), in the presence of an epoxy-terminated butadiene-acrylonitrile random copolymer (ETBN) , was studied as a function of the cure schedule and the initial rubber concentration.Fracture toughness (&) and fracture energy (GI,) were increased, while Young's modulus and yield strength decreased slightly with increasing volume fraction of the dispersed phase. We show that there is no significant influence of the precure schedule and of the various observed particle diameters on the mechanical properties for a constant rubber volume fraction. In our case, the main deformation process in the rubber-modified epoxy networks is shear yielding while cavitation is negligible.