title: Atomic-Oxygen-Durable and Electrically-Conductive CNT-POSS-Polyimide Flexible Films for Space Applications.
abstract: In low Earth orbit (LEO), hazards such as atomic oxygen (AO) or electrostatic discharge (ESD) degrade polymeric materials, specifically, the extensively used polyimide (PI) Kapton. We prepared PI-based nanocomposite films that show both AO durability and ESD protection by incorporating polyhedral oligomeric silsesquioxane (POSS) and carbon nanotube (CNT) additives. The unique methods that are reported prevent CNT agglomeration and degradation of the CNT properties that are common in dispersion-based processes. The influence of the POSS content on the electrical, mechanical, and thermo-optical properties of the CNT-POSS-PI films was investigated and compared to those of control PI and CNT-PI films. CNT-POSS-PI films with 5 and 15 wt % POSS content exhibited sheet resistivities as low as 200 Ω/□, and these resistivities remained essentially unchanged after exposure to AO with a fluence of ∼2.3 × 10(20) O atoms cm(-2). CNT-POSS-PI films with 15 wt % POSS content exhibited an erosion yield of 4.8 × 10(-25) cm(3) O atom(-1) under 2.3 × 10(20) O atoms cm(-2) AO fluence, roughly one order of magnitude lower than that of pure PI films. The durability of the conductivity of the composite films was demonstrated by rolling film samples with a tight radius up to 300 times. The stability of the films to thermal cycling and ionizing radiation was also demonstrated. These properties make the prepared CNT-POSS-PI films with 15 wt % POSS content excellent candidates for applications where AO durability and electrical conductivity are required for flexible and thermally stable materials. Hence, they are suggested here for LEO applications such as the outer layers of spacecraft thermal blankets.
authors.affiliation: †Space Environment Department, Soreq NRC, Yavne 81800, Israel.
authors.forename: Nurit
authors.initials: N
authors.lastname: Atar
authors.affiliation: †Space Environment Department, Soreq NRC, Yavne 81800, Israel.
authors.forename: Eitan
authors.initials: E
authors.lastname: Grossman
authors.affiliation: †Space Environment Department, Soreq NRC, Yavne 81800, Israel.
authors.forename: Irina
authors.initials: I
authors.lastname: Gouzman
authors.affiliation: †Space Environment Department, Soreq NRC, Yavne 81800, Israel.
authors.forename: Asaf
authors.initials: A
authors.lastname: Bolker
authors.affiliation: §Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
authors.forename: Vanessa J
authors.initials: VJ
authors.lastname: Murray
authors.affiliation: §Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
authors.forename: Brooks C
authors.initials: BC
authors.lastname: Marshall
authors.affiliation: §Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
authors.forename: Min
authors.initials: M
authors.lastname: Qian
authors.affiliation: §Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States.
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Minton
authors.forename: Yael
authors.initials: Y
authors.lastname: Hanein
keywords: CNT sheets; LEO space environment; POSS; atomic oxygen; electrical conductivity; nanocomposites; polyimide