THERMAL CHARACTERIZATION OF PETI-RFI FOR AIRCRAFT APPLICATIONS

摘要

Composite materials for application on naval aircraft must possess certain unique characteristics including toughness, resistance to temperature and moisture, and high specific strength. One resin system being investigated for potential airframe applications is PETI-RFI; an addition polyimide developed at NASA's Langley Research Center. Thermogravimetric analysis (TGA), modulated differential scanning calorimetry (MDSC), and rheology measurements were used to determine the cure kinetics, glass transition temperature (T_g), processing temperatures, and thermal decomposition kinetics. The resin system was cured for one hour at 371 deg C, to ensure complete cure. Cure kinetics, based on the variable heating rate method, exhibit an activation energy of 164.5 kJ/mol (39.3 kcal/mol). The measured behavior agrees with work reported by Hinkley on similar phenylethynyl-terminated compounds. Decomposition kinetics were investigated in order to assess high-temperature performance limits. Useful lifetime plots were incorporated based on the Toop equation, which allows the lifetime predictions based on the rate of resin weight loss.