Dynamic Foaming Behaviour of Polyurethane vs Tannin/Furanic Foams
Résumé
Simultaneously monitoring the variation of temperature, foam rising rate, internal foam pressure and dielectric polarisation, the latter being a direct measure of setting and curing of a thermosetting foam, has allowed the comparison of the dynamic variation of determinant parameters of polyurethane foams and of tannin/furanic foams of different formulation and characteristics. This monitoring provides a good description of the process and possible characteristics of the prepared foam and constitutes an invaluable tool for foam formulation. Such a comparison indicates that fundamental differences, but also similarities, exist between the foaming processes of the two classes of foam. The dynamics of the foams were compared for (i) a tannin/furanic foam formulation using formaldehyde and a low-boiling blowing agent (STD); (ii) a tannin/furanic foam containing neither formaldehyde nor blowing agent (MN65)., (iii) the same as (i) but with the addition of a small proportion of surfactant (MN8'), and (4) a commercial PUR foam formulation.