Untersuchungen Zur Stabilitaet der Zelloeffnung von Polyurethan-Weichschaeumen (Investigations of the Stability of the Cell Opening of Soft Polyurethane Foams)

摘要

The reasons for the stability of open-cell polyurethane foams and the parameters which influence their stability were investigated. The existing theories on cell opening and foam stability are reviewed. Two models were developed for the mathematical verification of the stability. The polyeder bubble model uses the finite difference method; results show satisfactory agreement with photographs. The second model describes the bubble growth in the foam and allows the determination of the geometry of the foam structure. It is found that an essential condition for foam stability is a sufficient strength of the viscous foam material. The strengthening of the liquid material depends only on the evolution of the chemical reactions. Thus, cell opening and foam stability are mainly a question of properly selected foaming recipe.