Wj. Muizebelt et al., OXIDATIVE CROSS-LINKING OF ALKYD RESINS STUDIED WITH MASS-SPECTROMETRY AND NMR USING MODEL COMPOUNDS, JCT, Journal of coatings technology, 70(876), 1998, pp. 83-93
Citations number
39
Categorie Soggetti
Chemistry Applied","Materials Science, Coatings & Films
The crosslinking of alkyd resins has been studied using ethyl linoleat
e and methyl ricinoate as model compounds. With quantitative C-13 NMR
is was established that ether- and peroxy-crosslinks were formed in ro
ughly equal amounts. Double bonds reacted to give epoxides, endoperoxi
des, and beta-scission into aldehydes. Using SIMS it was established t
hat dimers through pentamers were formed having included several oxyge
n atoms. After reduction of peroxide (crosslinks) with stannous chlori
de, the higher oxygen homologues decreased. In the NMR spectrum of the
reduced material, peroxide and epoxide signals completely disappeared
. High resolution electrospray ionization mass spectra (ESI-MS) yielde
d evidence regarding the crosslink mechanism. The non-conjugated linol
eic acid was found to crosslink by combination of radicals: dimers wer
e having masses 2(M-1). The conjugated linoleic acid crosslinked by ad
dition of radicals to the double bond and disproportionation, yielding
masses 2M as well. (M = mass of ethyl linoleate or methyl ricinoate,
respectively, including several oxygen atoms.) EIS-MS of oligomers aft
er isotopic exchange enable estimation of OH and OOH groups.