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Inherent Electrical Conductivity in Qualified Aircraft Transparency Materials
Navy SBIR 2010.2 - Topic N102-120 NAVAIR - Mrs. Janet McGovern - [email protected] Opens: May 19, 2010 - Closes: June 23, 2010 N102-120 TITLE: Inherent Electrical Conductivity in Qualified Aircraft Transparency Materials TECHNOLOGY AREAS: Air Platform, Materials/Processes ACQUISITION PROGRAM: PMA-265; F-18 Hornet, Super Hornet and Growler Program RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted." The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected. OBJECTIVE: Develop an inherently conductive transparency based on currently qualified transparency structural materials. DESCRIPTION: Aircraft transparency systems use one of several qualified materials as the transparent structural member. These include glass, cast acrylic, stretched acrylic, or polycarbonate [1-3]. In addition, transparency systems often include a layer of conductive material on the polymer ply. This conductive layer serves at least one of several possible functions including electrostatic dissipation, or electromagnetic interference shielding. The conductivity is usually provided by a metal or metal oxide in an ultra thin film, so as not to diminish the high optical transparency. This conductive layer, in turn, must be protected from environmental degradation by additional coatings, usually a thin polymer film or an additional ply of structural polymer. This layered approach creates multiple interfaces at which delamination can occur due to environmental exposure in service. These debonded areas act as optical scattering centers, degrading the optical transparency of the system. Delaminated areas require costly repair or replacement of the aircraft transparency system. Ultraviolet degradation and electrostatic discharge burn through are also issues with transparency coatings. A qualified transparency structural material is desired that has the conductivity "built-in" so that the metal coatings, and their attendant protective coatings and interfaces, could be eliminated. The optical properties of the system must be preserved. There have been numerous attempts to incorporate conductive fillers, such as carbon nanotubes or intrinsically conductive polymers, into optically clear materials, but the optical properties are often degraded to a point that would be unacceptable in an aircraft transparency application [4-7]. Additionally, this work is typically demonstrated in thin films not representative of aircraft transparency applications. PHASE I: Develop a material system concept with "built-in" electrical conductivity that provides optical and mechanical properties similar to currently qualified aircraft transparency materials. Demonstrate the technical feasibility of the concept through fabrication and testing of a few sub-scale coupons. The target sheet resistance would be less than 25 ohms/square while maintaining a transmissivity of greater than 80% and mechanical properties sufficient to qualify to the appropriate military material specification. PHASE II: Further refine and demonstrate the validity of the Phase I approach through scale-up and testing of prototypes of size and scale commensurate with application in aircraft transparency systems. Establish the performance parameters of the systems through systematic testing of prototypes. PHASE III: Transition the approach to a qualified transparency vendor for use on military and commercial aircraft. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Inherently conductive transparency materials have potential to transition to the commercial aircraft market. In addition, the development of clear conductive polymer materials has great potential in the area of optoelectronics. REFERENCES: 2. MIL-PRF-25690B � Plastic, Sheets And Formed Parts, Modified Acrylic Base, Monolithic, Crack Propagation Resistant, http://www.everyspec.com/MIL-PRF/MIL-PRF+(010000+-+29999)/MIL_PRF_25690b_2165/ 3. AMS-P-83310 � Plastic Sheet, Polycarbonate, Transparent. http://www.sae.org/technical/standards/AMSP83310 4. Du, F., Scogna, R. C., Zhou, W., Brand, S., Fischer, J. E., & Winey, K. I. (2004), Nanotube Networks in Polymer Nanocomposites: Rheology and Electrical Conductivity, Macromolecules, 37, 9048-9055. http://pubs.acs.org/doi/abs/10.1021/ma049164g 5. De, S., Lyons, P. E., Sorel, S., Doherty, E. M., King, P. J., Blau, W. J., Nirmalraj, P. N., Boland, J. J., Scardaci, V., Joimel, J., & Coleman, J. N. (2009). Transparent, Flexible, and Highly Conductive Thin Films Based on Polymer-Nanotube Composites, ACS Nano, 3 (3), 714�720. http://pubs.acs.org/doi/abs/10.1021/nn800858w 6. Hopkins, A. R.; & Reynolds, J. R. (2000), "Crystallization of Conducting Polymer Networks in Polymer Blends," Macromolecules, 33, 5221-5226. http://pubs.acs.org/doi/abs/10.1021/ma991347t?prevSearch=%255Btitle%253A%2BCrystallization%2Bof%2BConducting%2BPolymer%2BNetworks%2Bin%2BPolymer%2BBlends%255D&searchHistoryKey= 7. Ou, R., Gupta, S., Parker, C. A., & Gerhardt, R. A. (2006), Fabrication and Electrical Conductivity of Poly(methyl methacrylate) (PMMA)/Carbon Black (CB) Composites: Comparison between an Ordered Carbon Black Nanowire-Like Segregated Structure and a Randomly Dispersed Carbon Black Nanostructure, J. Phys. Chem. B, 110, 22365-22373. http://www.ncbi.nlm.nih.gov/pubmed/17091976 KEYWORDS: Transparency; Inherent Conductivity; Optically Clear; Polymer Materials; Nanocomposite; EMI Shielding
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