Abstract: The effects of hot air aging on static and dynamic mechanical properties of PBO/T700 hybrid composites were studied in this paper by using a universal testing machine and dynamic mechanical analysis (DMA). The static mechanical properties testing results indicate that the tensile strength and compressive strength of PBO/T700 hybrid composites declined after hot air aging, with maximum drop of 12.7% and 6.9%, respectively. The tensile modulus increased from 126 GPa to 145 GPa, while the flexural strength and modulus and the interlaminar shear strength of the composites show little changes. The DMA result shows that the heat-resistance property and rigidity of PBO/T700 hybrid composites increased to some extent after hot air aging. However, the E' and E″ of the composites shift toward low temperature and high temperature, respectively, with the increase of the aging time, which means some decline of heat-resistance property and rigidity of the composites.

Key words: PBO fiber, carbon fiber, hybrid composites, static mechanical properties, dynamic mechanical behavior