Selectively Strippable Silyl-Containing Aerospace Topcoats Using Environmentally Friendly Fluoride Salts
Abstract
The polyurethane topcoats used on the exterior of DoD aircraft and ground support equipment (GSE) are removed with hazardous chemical strippers, such as methylene chloride, abrasive materials, such as blast media and sand paper, or thermal ablation. However, all of these methods also damage the underlying nonmetallic substrate (e.g. anti-corrosive epoxy primer, carbon fiber reinforced composite) upon removal of the topcoat. Furthermore, a chemical stripper that is environmentally friendly, can selectively remove the polyurethane topcoat with minimal applications, and will not damaging the underlying non-metallic substrate does not currently exist. Herein, we have successfully demonstrated, as a proof-of-concept, that stimuli-responsive silyl-containing polyurethane (Silyl-PUs) coatings can provide similar thermal, mechanical, and performance properties (e.g. up to 60 percent GE Impact flexibility) as a MIL-PRF-85285 qualified polyurethane topcoat, yet also be selectively and completely removed (within 20 minutes) from a strongly adhered epoxy primer using an environmentally friendly fluoride salt solution under static conditions at room temperature (figure A1). Removal of the topcoat did not affect the chemical structure of the epoxy primer according to infrared analysis. The Silyl-PU technology, as a topcoat on aircraft, could prevent exposure of hazardous materials (e.g. hexavalent chromium) to workers and the environment by maintaining an intact epoxy primer upon selective removal of the topcoat, thereby reducing costs associated with hazardous waste disposal and reapplication of the primer.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 09, 2021
- Accession Number
- AD1191525
Entities
People
- Erick B. Iezzi
- Eugene Camerino
- Grant C. Daniels
- Keith B. Sutyak
Organizations
- United States Naval Research Laboratory