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Long‐term behavior of oil‐based varnishes and paints. Photo‐ and thermooxidation of cured linseed oil
Author(s) -
Mallégol Jacky,
Gardette JeanLuc,
Lemaire Jacques
Publication year - 2000
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-000-0042-4
Subject(s) - linseed oil , photochemistry , irradiation , degradation (telecommunications) , ultraviolet , chemistry , lability , infrared , fluorescence , materials science , organic chemistry , optics , telecommunications , physics , optoelectronics , computer science , nuclear physics
Thermooxidation at 100°C and photooxidation at wavelengths above 300 nm of dried oil films were evaluated. The chemical modifications of the networks were determined by infrared analysis coupled with gaseous treatments (NO, SF 4 , and NH 3 ). The dried films are rather stable in thermooxidation, whereas in photooxidation, important degradation of the network occurs with many chain scissions. This photoinstability results from the presence of crosslinks that are sensitive to radical attack because of the lability of the hydrogen atom on the tertiary carbons. The photooxidation reactions are fully described in this paper. Yellowing of the cured samples, observed with ultraviolet‐visible and fluorescence spectrometries, rapidly is decreased by irradiation because the oil contaminants that are mainly responsible for the yellowness are photooxidized. On the contrary, yellowing slowly but continuously increases during thermooxidation at 100°C.