Valorisation of Alfa stem in synthesis of lignin –phenol -formaldehyde resin: Application as an adhesive corrosion-resistant coating

Abstract

Abstract The physical-mechanical and chemical performances of phenolic resin in the wood industry are already highlighted. However, the manufacturing cost and the negative impact on the environment and the human health are too serious. Studies on lignin-based adhesives have been launched to develop an alternative raw material that is also reusable, from biosources for the synthesis of phenolic resins. In this work, we are interested in overcoming these constraints by using lignin, which contains phenolic groups, as a partial phenol substituent (50%) in the synthesis of phenol-formaldehyde (PF) resins. Lignin extracted by the alkaline method from renewable natural resource (the raw Alfa stem). Characterization analyses are used to confirm the chemical structure, the physical properties of the resin obtained from the substitution of 50% of the bio source lignin, their antioxidant and antibacterial activities are also tested. This allows the study of their antioxidant activity of DPPH and ABTS radical scavenging type, an antibacterial activity against E. coli and P. aeruginosa gram negative was observed for a concentration of 20 mg/mL. The obtained results, in contrasted with the industrial resin, showed high advantages of this substitution. Also, the obtained lignin can be directly influence the properties of the formulated resin (LPF), structurally because it is similar with the reference resin (CPF), quantitatively the low intensity of the peaks of the formulated resin is revealed to the limitations of the methylol groups compared to the CPF resin. Results also show good adhesion of lignin-based paint the coating containing CPF exhibited a good barrier property.