Characterization of tannin extracted from Aningeria altissima bark and formulation of bioresins for the manufacture of Triumfetta cordifolia needle-punched nonwovens fiberboards: Novel green composite panels for sustainability

Abstract

The new Aningeria altissima tannins extracted from ground bark were characterized by ATR-FT MIR and MALDI-ToF spectrometry. The tannin extracts were found to contain flavonoids and glucose, with a strong predominance of chalcone and gallocatechingallate monomers typical of condensed tannin proanthocyanidins. Two different formulations of resins bio-cured with hexamine and exudates from the Vachellia nilotica tree were analyzed (gel time, TMA and ATG) and used to manufacture biocomposite panels of carded-needled non-woven fibers of Triumfetta cordifolia (TC) natural fibers. The new biocomposites bonded with extracted Aningeria altissima tannin showed high water sensitivity, exceeding EN 622–5. The incorporation of TC fibers increased the thermal degradation temperature of biocomposites and improved their thermal stability. The mechanical properties of both biocomposites are high in the weft direction, which is favored by the preferential orientation of the fibers in this direction. In particular, the high flexural strength and flexural modulus are good enough to meet the specifications of current international standards for fiberboards used in dry conditions. The biocomposite with the optimum properties was obtained from fibers bonded with hexamine-cured tannin resin.