Bio-based phenolic foams from Anadenanthera peregrina tannins: Synthesis, structure and performance.

Tannin-based foams are natural-origin porous materials that offer promising alternatives to flammable synthetic foams due to their fire resistance and thermal insulation properties; however, their brittleness and relatively low mechanical resistance present challenges, necessitating improvements to these properties. This work aimed to investigate four types of tannin-based foams (ST, TT, TB, and TTB) prepared without formaldehyde, by using Anadenanthera peregrina tannins (ST) and the incorporation of polysorbate Tween 80 as a surfactant (TT), bamboo fibers as filler reinforcement (TB), and the combination of both polysorbate Tween 80 and bamboo fibers (TTB). In order to evaluate the effectiveness of the treatments on the foam properties, mechanical and chemical characterization was performed as well as SEM microscopy. Results indicated that the bamboo fibers and polysorbate Tween 80 addition to the formulations presented a minimal impact on the foam density maintaining values around 1383 ± 0,05 g·cm-3, and an average porosity of 87 %. Meanwhile, their incorporation led to a slightly improved compressive strength (0,12-0,19 MPa) and all the foams produced showed fireproofing and self-extinguishing behavior, demonstrating the potential of A. peregrina tannin-based foams for sustainable applications.