Cure Kinetic Study of Epoxy Systems for Advanced Composites and Surface Film Applications

ABSTRACT In this study, a comprehensive investigation is conducted to improve a surface film resin formulation for advanced composite applications. This surface film is designed to be co‐cured with a base substrate made of carbon fiber/epoxy‐based prepregs. The curing behavior of an epoxy resin formulation for a prepreg with a high glass transition temperature and a surface film formulation containing a high percentage of glass microspheres were characterized by isothermal and dynamic Differential Scanning Calorimetry, and rheometry; and the cure kinetics profiles were modeled. The effects of the curing system, glass microspheres, and accelerator on cure kinetics and rheological behavior were thoroughly investigated to assess the compatibility of these two resin systems to be used in a composite lay‐up. Initial trials resulted in excessive bleeding of the surface film resin, and specific improvements have been made to accelerate the reaction so that the system co‐cures without bleeding.