Tannin/furanic foams without blowing agents and formaldehyde

•Tannin/furanic foams without either formaldehyde or volatile organic blowing agents were prepared.•They presented good thermal insulation and better stress-strain characteristics.•Foams expansion, hardening, temperature and pressure variation were measured siumultaneously.•Tomography supported the different characteristics observed by stress-strain curves in compression.

Prorobinetinidin/profisetinidin type tannins have been used to prepare self-blowing tannin/furfuryl alcohol foams that do not need either formaldehyde or volatile organic blowing agents to prepare rigid foams. The 98% renewable materials foams so produced were even more environment-friendly, they presented equal thermal insulation and fire resistance and presented better stress-strain characteristics than tannin/furanic foams containing formaldehyde and organic blowing agents. Comparison of curves describing the simultaneously-measured foams expansion, hardening, temperature and pressure variation as a function of time allowed to show the differences in process and foaming parameters engendered by the differences in formulation of the experimental and control foams and optimisation of the foaming and hardening parameters involved. Tomography of the foams and foam controls produced supported the different characteristics observed for these foams obtained by stress-strain curves in compression.