Henri J. M. Grunbauer

An FT i.r. study of reaction kinetics and structure development in model flexible polyurethane foam systems

Abstract Forced-adiabatic, FT i.r. spectroscopy has been employed to simultaneously monitor polymerization and microphase separation on model flexible polyurethane foam systems. The following combinations of hydroxy functional components were investigated: (1) polyether-polyol and water; (2) polyether-polyol and deuterium oxide; (3) polyether-monol and water; and (4) polyether-monol and deuterium oxide. The formation of urethane, soluble urea, soluble d -urea, hydrogen-bonded urea and associated d -urea species were monitored during their fast bulk copolymerization with a diisocyanate. The decay of isocyanate is correlated to the polymerization kinetics and the evolution of hydrogen-bonded urea/associated d -urea is analysed emphasizing the onset of microphase separation of urea hard-segment sequences. The microphase separation transition (MST) occurred at a critical conversion of isocyanate functional groups. In the deuterium oxide blown foams, there was no trace of hydrogen-bonded urethane in the spectra obtained. In the polyether-monol systems, a lower conversion of isocyanate was observed at the MST and an overall lower reaction conversion was also observed.

Preparation of Isophorone Diisocyanate Terminated Star Polyethers

Reactive star shaped isocyanate prepolymers have been prepared by endcapping hydroxy functionalized poly(alkylene oxide)s with isophorone diisocyanate. Selective reaction conditions have been worked out to reduce the amount of chain extension and crosslinking due to reaction of both isocyanate groups of the IPDI moieties. By combining 1 H and 13 C NMR spectroscopy with size exclusion chromatography (SEC), the fractions of the monourethane isomers, and the extent of diurethane formation was determined. The effect of catalysis, of the excess of isocyanate, and of the type of poly(alkylene-oxide) on the product structure and composition were investigated.

Polymer morphology of water-blown rigid polyurethane foams : development of new polyols

ever, generation of more carbon dioxide is only one consequence of increased water levels in the polyol formulation. A second, equally important aspect is the relative increase of the number of urea bonds in the polymer backbone of the foam. Polymer morphology of a (partially) water-blown foam is therefore expected to be significantly altered with respect to an all-urethane foam. A systematic exploration of this effect has never appeared, although existing literature has been aware of the problem for a long time [1]. The present study attempts to fill the gap, at least partially, by analysing rigid foam polymers and their development during foam rise using DMS, on-line FTIR and SAXS The results