Exposure of polyphenylsulfone and polyphenylsulfone-hexagonal boron nitride composite films in the LEO wake environment

Polyphenylsulfone (PPSU) and polyphenylsulfone-hexagonal boron nitride (PPSU-hBN) composites were exposed to the low Earth orbit wake environment as part of NASA’s Materials International Space Station Experiment-13 (MISSE-13) Polymers and Composites Experiment-4 (PCE-4) to understand the aging behavior and durability of PPSU and the role of hBN filler after long-term exposure in a space environment. A post-flight visual inspection of the pristine PPSU and PPSU-10 wt% hBN flight samples showed discoloration from almost colorless to deep amber, which is likely attributed to light absorption in the wavelength of chromophores from the aromatic groups in PPSU. Attenuated total reflectance-infrared spectroscopy and Raman spectroscopy revealed changes in the C-S and ether linkages of the polymer, while thermo-gravimetric analysis shed insight into the mass loss rates between the pristine PPSU and PPSU-hBN depending on the environment.

Graphic includes Raman spectra of the control and flight specimens for pristine polyphenylsulfone. The middle image represents a post-flight image of polyphenylsulfone and polyphenylsulfone-boron nitride composite in UV and visible light. Profilometer images illustrates the roughness formed on the surfaces of the pristine polymer and composites after exposure to the low Earth orbit wake environment for 0.44 years.