THERMAL CHARACTERIZATION AND COMPARISON OF STRUCTURAL PREPREGS WITH DIFFERENT CURE TEMPERATURES

Two different epoxy based prepreg systems were characterized and compa red using thermal analysis. A prepreg system presently used in the com mercial airplane industry was compared with a prepreg system that is a prospective candidate for the same applications. The commercial syste m in use is a controlled flow resin prepreg system which is a 177 degr ees C cure system, while the prospective prepreg system is marketed as a dual prepreg system that can be cured at either 121 degrees C or 17 7 degrees C. Thermal characterization techniques including differentia l scanning calorimetry (DSC), dielectric analysis (DEA), and dynamic m echanical analysis (DMA) were used to investigate these systems. The d ifference in the curing mechanisms of both prepreg systems were identi fied through these thermal analysis techniques. Although, the kinetics of these systems were found to be vastly different their heats of rea ctions were very similar. The activation energies for the prepreg syst ems were determined by DSC using Kissinger's method and were found to be quite different. DMA measurements on autoclave cured composites dem onstrated that the prepregs obtained a different degree of cure as wel l as different glass transition temperatures (T-g). Furthermore, the u se of DEA and DMA demonstrated a difference in gelation of the two pre preg systems examined.