Four types of classical tannin-based foam samples were prepared via different methods in the current study with an attempt to find out the impact of each one on the physico-mechanical properties. The results of performed tests showed similarity to the general trend of related research, with typical negative relation between the foam density and mechanical strength. A critical point was found for each type of foam samples, for example, for tannin-formaldehyde foams (TFF), they were in the range of 85-95 kg/m3, while for tannin-glutaraldehyde foams (TGF), mechanically-generated tannin foams (MTF) and steam-driven tannin furanic foams (STDF), they were about 52-62 kg/m3, 53-63 kg/m3, and 73-83 kg/m3, respectively. This implies a significant change for density and mechanical strength, has been dig out by intensive experimental results and analysis. In addition, a non-liner relationship between density and pulverization ratio was obtained by fitting the curves obtained by the experiment results. Finally, visualization using scanning electron microscopy (SEM) together with evaluation of the compression strength presented a deeper insight to illustrate the different factors affecting foam density and pulverization ratio.
Keywords: foam; formaldehyde; glutaraldehyde; pulverization ratio; tannin.