title: Multifunctional Electroactive Nanocomposites Based on Piezoelectric Boron Nitride Nanotubes.
abstract: Space exploration missions require sensors and devices capable of stable operation in harsh environments such as those that include high thermal fluctuation, atomic oxygen, and high-energy ionizing radiation. However, conventional or state-of-the-art electroactive materials like lead zirconate titanate, poly(vinylidene fluoride), and carbon nanotube (CNT)-doped polyimides have limitations on use in those extreme applications. Theoretical studies have shown that boron nitride nanotubes (BNNTs) have strength-to-weight ratios comparable to those of CNTs, excellent high-temperature stability (to 800 °C in air), large electroactive characteristics, and excellent neutron radiation shielding capability. In this study, we demonstrated the experimental electroactive characteristics of BNNTs in novel multifunctional electroactive nanocomposites. Upon application of an external electric field, the 2 wt % BNNT/polyimide composite was found to exhibit electroactive strain composed of a superposition of linear piezoelectric and nonlinear electrostrictive components. When the BNNTs were aligned by stretching the 2 wt % BNNT/polyimide composite, electroactive characteristics increased by about 460% compared to the nonstretched sample. An all-nanotube actuator consisting of a BNNT buckypaper layer between two single-walled carbon nanotube buckypaper electrode layers was found to have much larger electroactive properties. The additional neutron radiation shielding properties and ultraviolet/visible/near-infrared optical properties of the BNNT composites make them excellent candidates for use in the extreme environments of space missions.
authors.affiliation: National Institute of Aerospace , Hampton, Virginia 23666, United States.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Kang
authors.affiliation: National Institute of Aerospace , Hampton, Virginia 23666, United States.
authors.forename: Godfrey
authors.initials: G
authors.lastname: Sauti
authors.affiliation: Advanced Materials and Processing Branch, NASA Langley Research Center , Hampton, Virginia 23681-2199, United States.
authors.forename: Cheol
authors.initials: C
authors.lastname: Park
authors.affiliation: National Institute of Aerospace , Hampton, Virginia 23666, United States.
authors.forename: Vesselin I
authors.initials: VI
authors.lastname: Yamakov
authors.affiliation: Advanced Materials and Processing Branch, NASA Langley Research Center , Hampton, Virginia 23681-2199, United States.
authors.forename: Kristopher E
authors.initials: KE
authors.lastname: Wise
authors.affiliation: Advanced Materials and Processing Branch, NASA Langley Research Center , Hampton, Virginia 23681-2199, United States.
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Lowther
authors.affiliation: Advanced Materials and Processing Branch, NASA Langley Research Center , Hampton, Virginia 23681-2199, United States.
authors.forename: Catharine C
authors.initials: CC
authors.lastname: Fay
authors.affiliation: Advanced Materials and Processing Branch, NASA Langley Research Center , Hampton, Virginia 23681-2199, United States.
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Thibeault
authors.affiliation: Advanced Materials and Processing Branch, NASA Langley Research Center , Hampton, Virginia 23681-2199, United States.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Bryant
keywords: boron nitride nanotubes; electroactive; nanocomposite; piezoelectric; radiation shielding