The mechanical properties of epoxy networks based on diglycidyl ether of bisphenol A epoxy resin cured with various linear aliphatic amines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and cyclic amines such as 1-(2-aminoethyl)piperazine and isophorone diamine, were studied. General characteristics such as T, density, and packing density, were determined and related to the structure and funcionality of the curing agent. Dynamic mechanical spectra were used to study both the a and P relaxations. Tensile and the flexural tests were used to determine the Young's and flexural modulus, and fracture strength all in the glassy state. Furthermore, linear elastic fracture mechanics was used to determine K-IC. As a rule, isophorone diamine network presented the higher tensile and flexure modulus while 1-(2-aminoethyl)piperazine gave the highest toughness properties. (C) 2007 Wiley Periodicals, Inc.