Release characteristics of polymer surface when moulding polyurethane foam

The polyurethane (PU) foam moulding process involves the use of sacrificial release agents (SRAs) that are both costly and harmful to the environment. This research proposes the use of low surface energy, polymer substrates, as a means of eliminating SRAs from the foam moulding process. Previous work identified the major factors affecting the ability of a polymer surface to release a PU foam part as being the surface energy and surface roughness of the substrate, and the proportion of isocyanate in the foam. The research described here has built upon these results and quantified the effects of each factor by using a D optimal design of experiment structure. Crucially it has also been shown that, given the surface energy of a polymer substrate, its roughness and the composition of the foam, it is possible to predict whether or not unaided release should be possible, and a model has been produced in order to allow this prediction for the foams under consideration. This capability will provide the PU foam moulding industry with the possibility of identifying polymeric mould materials, and levels of finishing for these moulds, which have the potential to allow the elimination of SRAs from the production process.