Characterization of photodegradation of a polyurethane coating by positron annihilation spectroscopy: correlation with cross-link density
| Autor: | Junjie Zhang, Peter E. Mallon, C.-M. Huang, T. C. Sandreczki, Y.C. Wu, R. Zhang, Hongmin Chen, Yong Li, Yan Ching Jean |
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| Rok vydání: | 2001 |
| Předmět: |
Annihilation
Materials science General Chemical Engineering Organic Chemistry Analytical chemistry Spectral line Surfaces Coatings and Films Positron annihilation spectroscopy chemistry.chemical_compound chemistry Materials Chemistry medicine Irradiation Swelling medicine.symptom Methylene Photodegradation Doppler broadening |
| Zdroj: | Progress in Organic Coatings. 42:244-252 |
| ISSN: | 0300-9440 |
| DOI: | 10.1016/s0300-9440(01)00200-4 |
| Popis: | Photodegradation of a polyurethane coating by Xe arc-lamp irradiation as a function of time is studied by positron annihilation spectroscopy. Doppler broadening energy spectra (DBES) of annihilation irradiation is measured as a function of incident positron energy (0–30 keV). A significant decrease in the S -defect parameter from DBES is observed as a function of irradiation time. This is interpreted as a loss of free-volume and holes during the photodegradation process. The cross-link density in the same system is measured by a solvent (methylene chloride) swelling method and is found to increase as a function of irradiation time. A direct correlation between the increase in cross-link density and the decrease in the S -defect parameter from the DBES data is observed. These results are used to discuss the photodegradation process in terms of chemical and physical changes due to UV-irradiation in protective polymeric systems. |
| Databáze: | OpenAIRE |
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