Photo-initiation rate behavior of weathered coatings: ESR-nitroxide decay assay
1988; Elsevier BV; Volume: 20; Issue: 2 Linguagem: Inglês
10.1016/0141-3910(88)90081-x
ISSN1873-2321
AutoresJ.L. Gerlock, Deborah F. Mielewski, David R. Bauer,
Tópico(s)Electron Spin Resonance Studies
ResumoA procedure is described to extend the nitroxide decay assay measurement of coating photo-initiation rates to weathered coatings. The procedure involves post-cure doping of coatings with 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy free radical in the presence of CH2Cl2/CH3OH vapor at 60°C. The photo-initiation rates of three acrylic-melamine coatings have been followed as a function of 'QUV-light only' accelerated exposure. For each of these coatings, the photo-initiation rate drops during the first 10–20 h of exposure and then remains constant at a level indicative of their weatherability for the duration of the exposure. No evidence is found for autoxidation in these coatings.
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