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The sensitization of 3 photoinitiators was studied by FTIR spectroscopy. The tested initiators were: HP1 – ( 5-2,4-cyclopentadien-1-yl){(1,2,3,4,5,6- )-{-[4-(2-hydroxy-2-methylpropanoyl)-phenoxy]ethoxy}-benzene}-Fe(II)-hexafluorophosphate) prepared in our laboratory and two commercially available photoinitiators for comparison (radical photoinitiator (1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methylpropan-1-on) and cationic photoinitiator ( 5-2,4-cyclopentadien-1-yl)-[(1,2,3,4,5,6- )-chlorobenzene]-Fe(II)-hexafluorophosphate). HP1 contains chemical groups suitable for starting free radical and cationic polymerization simultaneously.
Isopropyl thioxanthone and anthracene were used as sensitizers (concentrations 0.5 and 1 molar %). Molar absorption coefficients of photoinitiators and sensitizers were determined by UV-VIS spectroscopy. The sensitization of photoinitiators was examined in acrylate monomer (pentaerythritol triacrylate) and epoxy monomer (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate) under O2 and O2-free condition. Results proved that hybrid photoinitiator HP1 can be efficiently sensitized in epoxide monomer. Sensitization of photoinitiators in acrylate monomer was efficient only in presence of oxygen whereas in absence of oxygen was ineffective.
Key words: photoinitiator, sensitization, UV-VIS, FTIR, UV polymerization
