Characterization of Epoxy Prepreg Curing Process

The isothermal and dynamic curing process of epoxy composite was studied using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and other techniques. The variation of degree of curing with time and temperature was analyzed. The degree of curing was limited at any particular temperature because of the diffusion control in isothermal curing process. Half-life and maximum cure time were discussed in the analysis of the isothermal curing process. The modeling result from isothermal curing process indicated that degree of curing calculated with diffusion control agreed well with experimental data. The degree of curing calculated by two methods for dynamic curing process had a deviation with experimental data in either earlier or later cure stages. The relationship between T-g and the degree of curing was described by two models. Both models agreed well with the experimental T g . The isothermal curing diagrams of time-temperature-transformation (TTT) and conversion-temperature-transformation (CTT) were constructed. Each region in TTT and CTT diagrams corresponded to the phase state of the curing process, so that the curing mechanism was clearly reflected in diagrams. The thermal stability analysis indicated the epoxy resin system was very thermally stable under temperature of 300 degrees C.