Role of silicone surfactant in flexible polyurethane foam

X. D. Zhang, C. W. Macosko, H. T. Davis, A. D. Nikolov, D. T. Wasan

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

Grafted copolymers which consist of a polydimethylsiloxane backbone and polyethylene oxide-co-propylene oxide pendant groups are used as surfactants to stabilize the foam cells in the flexible polyurethane foaming process. The mechanical properties of the cured polyurethane foam such as air permeability and foam cell size are affected significantly by the structure of the silicone surfactant used in the formulation. It is shown that silicone surfactant has an important impact on both the bubble generation and the cell window stabilization stage. A series of silicone surfactants with different structures was tested. Surfactants with higher silicone content will provide lower surface tension and thus help increase the number of air bubbles introduced during mixing. These air bubbles serve as the starting point for foam cell growth. As a result, the cured polyurethane foam made with higher silicone content surfactant has a smaller bubble size. It is also shown that silicone surfactant can reduce the cell window drainage rate due to the surface tension gradient along the cell window. The Gibbs film elasticity, the dynamic film elasticity, and the film drainage rate were measured for the first time versus surfactant composition. Surfactants with longer siloxane backbones are shown to give higher film elasticity. Using the vertical film drainage and foam column tests, it is shown that surfactants with higher film elasticity will yield slower drainage rate and better foam cell stability.

Original languageEnglish (US)
Pages (from-to)270-279
Number of pages10
JournalJournal of Colloid And Interface Science
Volume215
Issue number2
DOIs
StatePublished - Jul 15 1999

Bibliographical note

Funding Information:
The surfactants used in this study are synthesized by Witco Corp., Osi Specialities Group. Support for this research was provided by the Center of Interfacial Engineering, a NSF engineering research center at the University of Minnesota. Part of the bubble formation and foam column tests were performed by Ms. Lise Bertsch.

Keywords

  • Film drainage
  • Film elasticity
  • Film tension
  • Foam stability
  • Nucleation
  • Polyurethane foam
  • Silicone surfactant

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