A novel approach to the assessment of aerospace coatings degradation: The HyperTest
| Autor: | Marie-Laure Abel, Taraneh Bozorgzad Moghim, John F. Watts |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Ozone General Chemical Engineering 02 engineering and technology engineering.material 010402 general chemistry 01 natural sciences Matrix (chemical analysis) chemistry.chemical_compound Coating X-ray photoelectron spectroscopy XPS Materials Chemistry Organic chemistry Chemical decomposition Polyurethane coating chemistry.chemical_classification Organic Chemistry Polymer 021001 nanoscience & nanotechnology Accelerated test 0104 chemical sciences Surfaces Coatings and Films chemistry engineering Chemical Engineering(all) Degradation (geology) Limiting oxygen concentration Aerospace coating 0210 nano-technology Nuclear chemistry |
| Zdroj: | Progress in Organic Coatings. 104:223-231 |
| ISSN: | 0300-9440 |
| DOI: | 10.1016/j.porgcoat.2016.11.008 |
| Popis: | Protecting an aircraft from the extremes of environments during service begins at the interface between topcoat and environment. The topcoat considered here is an aliphatic polyurethane (PU) based matte coating. This paper examines the degradation of the PU topcoat through the use of a novel HyperTest which combines ultra-violet (UV) and ozone as the degradation method. To benchmark the technique against accepted accelerated testing methods, QUV was used and samples were tested between two and 56 days. For The HyperTest, samples were degraded at increments between one to 120 minutes. X-ray photoelectron spectroscopy (XPS) determined that 56 days of UV exposure was equivalent, in terms of the extent of the chemical degradation of the topcoat, to one to two minutes of UV/ozone (UV/O3) exposure. There was a significant increase in carbonyl component with increasing oxygen concentration for samples treated with The HyperTest, whereas no clear degradation trend was observed for the samples exposed to UV alone. After 60 minutes of UV/O3 exposure a steady-state mechanism is established as the oxidative decomposition of the PU coating. The proposed degradation mechanism of the PU topcoat, through UV/O3 exposure, is the reaction of atomic oxygen with the polymer matrix/binder through hydrogen abstraction producing a hydroxyl group. This further decomposes to produce a carbonyl component observed in the XPS analysis. The products of degradation are simple volatile molecules such as CO2 and H2O for both testing methods used here. However, the efficient nature of The HyperTest, requiring only minutes to degrade samples as shown here, proves it to be a viable complementary technique to established methods of laboratory accelerated testing. |
| Databáze: | OpenAIRE |
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