The design of next-generation air- and spacecraft necessitates the development of high strength-to-weight ratio materials. Specifically, carbon fiber reinforced polymers (CFRPs) are used to improve aeronautical range of commercial aircrafts, maneuverability of military jets, and payload capacity of space-bound rockets. Polybenzoxazine (BOX) networks represent an appealing new chemistry for CFRPs with the potential to replace traditional epoxy-based matrices due to their excellent shelf-life stability, minimal chemical shrinkage, synthetic modularity, and high performing thermomechanical properties. Low Earth Orbit (LEO) is a notoriously hazardous environment for organic materials due to high levels of ultraviolet radiation (UV) and atomic oxygen (AO). A variety of techniques have been developed to impart UV- and AO-resistance to organic composites, such as the application of coatings or the blending of nanoparticles. More recently though, it has been found that chemical incorporation of passivating functional groups, like phenylphosphine oxide (PPO), into the polymer’s backbone offers greater protection and is a more economical solution than applying and maintaining secondary coatings. Although PPO has been proven in polyimide systems, the viability of PPO-modified BOX for UV- and AO-resistance is not well understood. In this study, phenylphosphine oxide functional BOX (PPO BOX) was synthesized to probe PPO’s effects on network thermomechanical and photooxidative properties, and the protective mechanism of PPO BOX was investigated. This research would provide fundamental knowledge on the network properties of PPO BOX and its behaviour in extreme environments such as LEO.

Phenylphosphine oxide functional benzoxazine as low earth orbit stable composite matrix polymers

2019 Spring National Meeting

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