Quantitative determination of unsaturation in photocured halogenated acrylates and methacrylates by FT-IR and Raman-spectroscopy and by thermal analysis

The photo-polymerization of tetrachloroethylacrylate (TeCEA), pentafluoroph enylacrylate (PFPA) and pentafluorophenylmethacrylate (PFPMA) was examined by quantitative FT-IR and FT-Raman spectroscopy and by thermal analysis. Th e agreement between the FT-Raman results and thermal analysis was good for all monomers. The FI-IR measurement yielded higher percentages of unsaturat ion than the two other techniques in the slowly reacting PFPMA polymer, whi ch can be attributed to oxygen quenching effects. Calculations of unsaturat ion based on spectroscopic measurements were carried out using the relative band ratio method. The influence of the choice of the internal reference b and on the unsaturation calculation was examined. The photo-polymerization of the acrylates reached conversions of 95%-99% after irradiation of only a few minutes, samples which contained PFPMA reached conversions of about 85 % after 1.5 h of irradiation. Volatile compounds in the resulting polymers were quantified and identified by thermogravimetic analysis (TGA) and therm al desorption followed by gas chromatography with mass spectrometric detect ion (TD-GC-MS), respectively. Glass transition temperatures of the resultin g polymers as determined by differential scanning calorimetry (DSC) vary fr om 70 degrees C to 125 degrees C. (C) 1999 Elsevier Science Ltd. All rights reserved.