Formaldehyde-Free Prorobitenidin/Profi setinidin Tannin/Furanic Foams Based on Alternative Aldehydes: Glyoxal and Glutaraldehyde

Tannin/furanic foams, typically 95% composed of materials of natural origin such as prorobinetinidin/profisetinidin tannins and furfuryl alcohol, are potential alternatives to oil-based synthetic foams such as phenol-formaldehyde, and polyurethane foams. This article describes the development of second generation tannin/furanic foams, which are not only formaldehyde free, but also use nonvolatile, nontoxic aldehydes. Both glyoxal and glutaraldehyde were tried to substitute formaldehyde in tannin/furanic foams. The physical properties of these new foams are described and discussed. It was found that glutaraldehyde can totally substitute formaldehyde during tannin/furanic foam preparation, but that glyoxal cannot. The optimized proportion to prepare such new foams is tannin:glutaraldehyde = 30:4 by weight. Formaldehyde-free glutaraldehyde-containing foams are open-celled and present good compression resistance and high thermal insulation.