Broadband dielectric spectroscopy, heat capacity spectroscopy (3ω method), and viscosimetry have been used to study the dynamic glass transition of two glass-forming epoxy resins, poly [(phenyl glycidyl ether)-co-formaldehyde] and diglycidyl ether of bisphenol-A. In spite of their rather simple molecular structure, the dynamics of these systems is characterized by two well-separated crossover regions where the relaxation times of main transition and the two secondary relaxations β and γ approach each other. The main transition has three parts: The a process at high temperature, the a' process between the two crossover regions, and the a process at low temperatures. Both the γ-crossover region [around a temperature T[sub c](γ)∼ (1.4-1.5)Tg and a relaxation time Τ[sub c](γ) ≈ 10[sup -10] S] and the β-crossover region [around T[sub c](β)∼(1.1-1.2)T[sub g] and Τ[sub c](β) ≈10[sup -6] s] could be studied within the experimentally accessible frequency-temperature window. Different typical crossover properties are observed in the two regions. The γ-crossover region is characterized by onset of the (a', α) process, with a relaxation time about one decade greater than that of the quasicontinuous (a, γ) trace. The β-crossover region is characterized, besides splitting of main and β relaxation times, by a change in the temperature dependence of the main-relaxation time as reflected by a bend in the Stickel plot of the continuous (a', α) trace, the separation of individual temperature dependences of different transport properties such as impurity-ions diffusion coefficient and viscosity, and a temperature-dependent main relaxation time that starts to be in accordance (at lower temperatures) with the Adam-Gibbs model. The cooperativity of the main process between the y and β crossover seems to be small. Below the β crossover, cooperativity increases up... [ABSTRACT FROM AUTHOR]