Mechanism of photo stabilization of perfluoropolyether coatings by hindered amine stabilisers

Citation
Mp. Luda et al., Mechanism of photo stabilization of perfluoropolyether coatings by hindered amine stabilisers, POLYM DEGR, 73(3), 2001, pp. 387-392
Citations number
8
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
POLYMER DEGRADATION AND STABILITY
ISSN journal
0141-3910 → ACNP
Volume
73
Issue
3
Year of publication
2001
Pages
387 - 392
Database
ISI
SICI code
0141-3910(2001)73:3<387:MOPSOP>2.0.ZU;2-#
Abstract
Perfluoropolyethers show promising properties for coil coating application and a suitable layer is obtained by incorporating them in a crosslinked pol yurethane, network. However, photo-oxidative stability of urethane linkages is intrinsically low and an appropriate stabiliser must be added to the re actants prior to curing. The N-methyl HAS bis(1,2,2,6,6-pentamethyl-4-piper idyl) sebacate (Tinuvin765) has been selected for this model study. The che mical structure of the network strongly depends on the curing conditions: c oil coating conditions (280 degreesC/1 min in air) lead to a polyurethane n etwork also containing some urea-bridges and unreacted isocyanate. HAS furt her modifies the network increasing the urea-bridges at the expenses of the unreacted isocyanate. This kind of network is shown to be intrinsically mo re resistant to the photo-oxidation than pure polyurethane. In curing condi tions the N-methyl HAS is partially transformed into -NH derivatives which are still active antioxidants. During photo-oxidation HAS acts as a radical scavenger but slowly evaporates from the film. (C) 2001 Elsevier Science L td. All rights reserved.