کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5204327 | 1381957 | 2009 | 10 صفحه PDF | دانلود رایگان |
The photooxidation of poly(N-vinylpyrrolidone) (PVP) in the solid state and in an aqueous solution has been studied under irradiation at long wavelengths (at λ â¥Â 300 nm) and in the presence of oxygen, as these conditions of irradiation are those of natural outdoor aging. Infrared spectroscopy was used to follow the photochemical evolution of the polymer either for solid films of PVP or for PVP irradiated in an aqueous solution. Chemical treatments (NH3, SF4) were carried out on the photooxidized samples, and aqueous solutions of PVP were characterized by viscometry and size exclusion chromatography (SEC). Based on photooxidation results obtained in both the solid state and in an aqueous solution, a general mechanism that accounts for the main routes of oxidation is proposed. It was shown that the rates of oxidation and the stoichiometries of the reactions were strongly influenced by the physical state of the polymer (solid state or aqueous solution).
Journal: Polymer Degradation and Stability - Volume 94, Issue 12, December 2009, Pages 2257-2266