This work explores the characterization of pre-impregnated ("prepreg") materials made with an epoxy resin/carbon fiber, using FT-IR spectroscopy, thermogravimetry (TG), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). FT-IR spectroscopy was used in the transmission mode (KBr pellets, pyrolysis without control and controlled pyrolysis) and photoacoustic detection (FT-IR/PAS). The transmission FT-IR spectra revealed the presence of epoxy resin, cyano groups, amine and bisphenol A, which allowed us to identify the probable agent of cure: cyanoguanidine (or DCD). With FT-IR/PAS it was possible to monitor spectrometric changes caused by curing. The thermal analysis assisted in observing and understanding events during the curing process, including the gelation and vitrification steps. It was also useful to study the influence in the glass transition temperature (Tg) of the cured material and for choosing the curing temperature range, which is one of the main parameters in the manufacturing process.
Characterization; composite; epoxy resin; cure; FT-IR; thermal analysis