POSS-Polyimide Nanocomposite Films: Simulated Hypervelocity Space Debris and Atomic Oxygen Effects

Abstract

The combined effect of hypervelocity space debris impact and atomic oxygen (AO) attack on the degradation of reinforced polyhedral oligomeric silsesquioxanes (POSS)-polyimide films was studied. A laser-driven flyer (LDF) system was used to accelerate aluminum flyers to impact velocities of up to 3 km s -1. The impacted films were exposed to an RF-plasma source, which was used to simulate the effect of AO in the low Earth orbit. Scanning electron microscopy (SEM) was used to characterize the fracture morphology. The extent of damage in POSS-polyimide impacted films was found to be much smaller compared to POSS-free films, insinuating on a toughening mechanism developed due to POSS incorporation. When exposed to air RF-plasma, the impacted POSS-free film revealed a synergistic effect associated with a large increase in the erosion rate while impacted POSS-containing samples showed improved erosion resistance. The increased erosion rate of the impacted POSS-free film is explained by formation of residual stresses that affect the oxidation mainly by increasing the diffusivity of oxygen.

Characterization and analysis on atomic oxygen resistance of POSS/PVDF composites

“…The following amendment for the simulation of atomic oxygen erosion was employed based on the empirical equation and the reported experimental results [21,[25][26][27]: (1) No interaction occurs between POSS and atomic oxygen under high atomic oxygen fluence since the impact energy is not able to break the bond of POSS. (2) Heat reaction will not occur between atomic oxygen and composite as POSS absorbs the impact energy produced by atomic oxygen (3) according to relevant references [16,26,28], the erosion yields for 3% and 10% POSS/PVDF are = 1.24 × 10 −25 cm 3 /atom and = 0.8 × 10 −25 cm 3 /atom, respectively.…”

Evolution of surface chemistry and morphology of hyperbranched polysiloxane polyimides in simulated atomic oxygen environment

“…As is reported, polyimide coated with TiO 2 or SiO 2 has exhibited superior AO resistance than unprotected one [3,16]. However, inherent and hypervelocity debris-induced defects within the coating will permit AO attack of the underlying polymer, although the SiO 2 coating itself is highly resistant to AO [17]. Therefore, rational design focusing on the molecular modification of polymeric materials, other than coating technology, is the key to manufacture new polyimides with desirable AO resistance.…”

Debris/Micrometeoroid Impacts and Synergistic Effects on Spacecraft Materials

“…The new macro-hole formation is a result of a multistep process that includes the establishment of a field of residual tensile stresses within the polymer due to the hypervelocity impact. 32 In addition, an increase in the polymer's local free volume occurs, 34 leading to increased molecular and AO diffusion into the polymer. Consequently, a local increase in the AO-induced erosion rate takes place, [35][36][37] resulting in the formation of new macro-holes.…”

“…It was suggested that due to the hypervelocity impact, a residual tensile stress field is developed within the polyimide. 32,33 A model was proposed to explain the extensive erosion and the formation of the new holes in the impacted polyimide film due to AO exposure in the oxygen radio frequency plasma. The new macro-hole formation is a result of a multistep process that includes the establishment of a field of residual tensile stresses within the polymer due to the hypervelocity impact.…”