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This work valorizes bio-hardeners from the Far North region of Cameroon, such as the exudates of Senegalia senegal, Vachellia seyal, Acacia siebteriana, and Vachellia nilotica. They were used to manufacture particleboard based on Maritime pine tannin resin, marketed to find a palliative solution to the environmental problems posed using synthetic hardeners such as paraformaldehyde. The rigidity values of the tannin resin vary from 4337 MPa at 154°C for the lowest to 5341 MPa for the highest at pH = 3.5. The behavior of the manufactured 13 mm thick particleboards of medium density was determined by calculating the variation of the bending strength (MOR), modulus of elasticity (MOE), and internal bond (IB) as a function of densities. The values of MOE vary between 1960.20 MPa and 3067.93 MPa and those of MOR between 13.17 MPa and 20.39 MPa. The maximum values of IB and Brinell hardness (HB) are 0.60 MPa and 3.78 daN/mm2 respectively. These physical and mechanical properties increased with increasing densities. The particleboards made with these bio-hardeners had better properties than those made with paraformaldehyde as hardener. The particleboard made with Vachellia nilotica exudate had the best physical and mechanical properties. [ABSTRACT FROM AUTHOR]

Gilbertiodendron dewevrei tannin extract was characterized using MALDI–ToF and CP MAS 13C NMR methods. These two characterization methods have proven that catechin gallate is the dominant constituent. Subsequently, the G. dewevrei tannin bio-resins hardened with the exudates of Vachellia nilotica, Vachellia seyal, Senegalia senegal, Acacia siebteriana and the fruit powder of V. nilotica from the extreme north of Cameroon were studied using gel time analysis and thermomechanical analysis. Analysis indicated that the cross-linking species in these hardeners was 2,5-dihydroxymethyl furan linked to carbohydrate chains. The extracts obtained in comparison to paraformaldehyde cured adhesives in equal proportions (10%) show that the 'biohardener' had properties for adhesive and eco-friendly applications. The internal bond (IB) strength of G. dewevrei resin-bonded panels using biohardeners ranged from 0.46 MPa to 0.61 MPa, the MOE and MOR values were from 1880.23 to 2226,52 MPa and 14,17 to 16,41 MPa. All particleboards prepared presented exterior grade capabilities. [ABSTRACT FROM AUTHOR]