Abstract
The mechanisms which control the formation and the final configuration of the cellular structure of a flexible foam are not completely understood. This also applies to the relationship between this structure and foam properties. An indepth investigation of these two aspects has been initiated with a specific interest for MDI-based cold cure foams. It is aimed in a first instance at building up a good understanding of the phenomena mentioned above. This will then be used in the development of new PU formulations more fitted to market needs by considering the optimisation of the cellular structure to meet the required properties.
In this respect, an automated method for quantifying the cellular structure of flexible foams has been defined. The quantification is made by reconstructing cut cells of a foam cross-section by using recent developments of image analysis techniques. The method allows fast measurement and has been optimised to be suitable for a wide range of flexible foams.
Using selected parameters from the measurements representative of the cell size and cell size distribution, it willbe shown that this method gives a statistical description of the structure and that reproducible results are obtained.
It willbe shown that the measurements can be applied to practical situations. The effect of the mixing conditions of the reactants on the foam structure will be quantified and different mixing technologies will be compared. Achievements in controlling the cellsize of polyurethane flexiblefoams willbe presented and some correlations with foam properties willbe discussed. Finally it willbe shown how the defined method can be used as a classification of foam by its cellular structure and a scale will be proposed.
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