Resistance of POSS Polyimide Blends to Hyperthermal Atomic Oxygen Attack

Area of Science:

• Materials Science
• Polymer Chemistry
• Aerospace Engineering

Background:

• Polyhedral oligomeric silsesquioxane (POSS) and polyimide (PI) copolymers exhibit high resistance to atomic oxygen (AO) in low Earth orbit (LEO).
• POSS PI blends present a potentially economical alternative if they also possess AO resistance.

Purpose of the Study:

• To evaluate the atomic oxygen resistance of trisilanolphenyl (TSP) POSS and PI blends.
• To compare the performance of POSS PI blends with existing POSS PI copolymers.

Main Methods:

• Films of TSP POSS PI blends with varying POSS content were fabricated.
• Materials were exposed to a hyperthermal AO beam.
• Characterization included recession, mass loss, surface morphology (SEM), and surface chemistry (XPS).

Main Results:

• AO resistance improved with higher AO fluence and increased POSS loading for all POSS PI materials.
• TSP POSS PI blends showed erosion yields comparable to POSS PI copolymers at similar POSS loadings.
• Passivating SiO_x layers formed on POSS-containing polymer surfaces during AO exposure.

Conclusions:

• TSP POSS PI blends offer a low-cost, high-performance option for spacecraft materials in LEO.
• The formation of SiO_x layers contributes to the AO resistance of these materials.