- Author
-
Abouelezz, M.
|
Waters, P. F.
- Title
- Studies on the Photodegradation of Poly(Methyl Methacrylate).
- Coporate
- National Bureau of Standards, Washington, DC
American Univ., Washington, DC
- Report
-
NBSIR 79-1766
June 1979
49 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
polymethyl methacrylate
|
degradation
|
photogradation
|
ultraviolet
|
unzipping
|
visible
- Abstract
- When poly (methyl methacrylate), PMMA, is exposed to sunlight, it gradually degrades and, after long-term exposures, may be unable to perform its intended functions. While the photodegradation of PMMA has been studied extensively using radiation sources below 300 nm, natural sunlight at the earth's surface does not extend below 292 nm. This study was performed in order to examine the effect of the radiation from the upper part of the ultraviolet, UV, and the visible regions on PMMA and to identify the mechanism(s) of degradation induced by the radiation. Thin films of PMMA were irradiated in air with upper UV, upper VU-visible, upper UV-visible-near infrared and 436 and 546 nm radiation. Exposure to either the upper UV or visible radiation caused degradation of the polymer. The data show that both random scission and unzipping of the polymer chain are operative in the degradation. Unzipping becomes increasingly important with incident radiation of increasing wavelength.