Fourier Transform Infrared Studies on Deblocking and Crosslinking Mechanisms of Some Fluorine Containing Monocomponent Polyurethanes

Abstract

The thermal reactivity of a set of different blocked perfluoropolyether (PFPE) containing polyisocyanates and one monocomponent polyurethane containing a PFPE diol was investigated by Fourier transform infrared (FT-IR) spectroscopy. With the former series of products the deblocking kinetics at 90 °C and 120 °C were investigated with time-dependent spectral data, showing the highest thermal deblocking activity for 3,5 dimethylpyrazole blocking agent. The crosslinking reaction of the PFPE diol with ketoxime blocked isocyanurate at 150 °C was monitored by infrared (IR) spectroscopy and two-dimensional (2D) correlation analysis; the results suggested a prevailing direct condensation mechanism and the formation of urea byproducts in the later stages of reaction. Both synchronous and asynchronous spectra were considered and discussed, pointing out the time relation of the chemical functions during the crosslinking experiment.

Keywords

Crosslinking mechanism Polyurethane Infrared spectroscopy

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