Integrated view of reactive urethane foaming

L. D. Artavia, C. W. Macosko, R. D. Priester, A. K. Shrock, R. B. Turner

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Scopus citations

Abstract

During flexible foam processing, the isocyanate-water reaction forms urea dimers and oligomers, which eventually segregate as a microdisperse solid phase. An understanding of the fundamental role that urea segregation plays on reaction kinetics and flowability during foaming is the purpose of this work. Temperature and volume rise profiles were measured for a series of flexible foam systems by varying the amount of water (2-6 pphp), isocyanate (90, 110, 130 index) or catalyst package in the formulation. Model calculations showed that 84-90% conversion of isocyanate groups was required to form a crosslinked polymer network. However, volume rise was found to stop at 40-70% isocyanate conversion. This indicates that gelation is due to phase separation rather than covalent crosslinking. Furthermore, a sudden acceleration in the rate of reaction (dT/dt) was consistently detected prior to foams reaching a constant volume. A mechanism is presented to correlate temperature and volume rise profiles with urea microphase segregation during reactive urethane foaming.

Original languageEnglish (US)
Title of host publicationPolyurethanes World Congr 91
PublisherPubl by Technomic Publ Co Inc
Pages509-518
Number of pages10
StatePublished - Dec 1 1991
EventPolyurethanes World Congress 1991 - Nice, Fr
Duration: Sep 24 1991Sep 26 1991

Other

OtherPolyurethanes World Congress 1991
CityNice, Fr
Period9/24/919/26/91

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