Thermal deblocking of masked low molecular isocyanates I. Aliphatic isocyanates

The thermal deblocking of masked isocyanate model substances was investigat ed by means of simultaneous thermal analysis and quadrupole mass spectromet ry system (STA/QMS). The results were compared with additional measurements carried out by differential scanning calorimetry (DSC) and temperature dep endent Fourier transform infrared spectroscopy (FTIR). The measured values which were determined as the deblocking temperature depend on the method of investigation. Thermogravimetric and mass spectrometric data depend on the volatility of the components and could differ from those observed by DSC a nd/or FTIR. Furthermore, the mechanism of deblocking is very complex. Secon dary reactions obviously play an important role. (C) 2000 Elsevier Science B.V. All rights reserved.