Phenolic adhesives, primarily made of petroleum-based phenol and formaldehyde, have been used for many decades to manufacture wood composites such as plywood and oriented strand board (OSB) due to their superior performance. Phenol and formaldehyde are both made of fossil-fuel chemicals, and formaldehyde's toxicity and carcinogenic activity caused many researchers to focus on finding ways to replace it with biobased, less toxic raw materials. This study was focused on using lignin, a natural plant-based polymer, to replace phenol and used glyoxal, a biobased non-toxic chemical, to replace formaldehyde. The phenol was entirely replaced with an unmodified enzymatic hydrolysis corn stover lignin, while at the same time formaldehyde was substituted from 0 to 100% in increments of 10 with glyoxal. The resins were formulated under alkaline conditions using lignin to formaldehyde and/or glyoxal with a 1:2 molar ratio. The property and performance of resins and adhesives were measured and compared to a phenol-formaldehyde (PF) adhesive formulated in the lab. The pH, alkalinity, solid-content, free formaldehyde content of the formulated adhesives was similar to a commercially available PF adhesive. The dry lap shear strength of the developed lignin-glyoxal (LG) adhesive was 3.3 ± 0.4 MPa, which was comparable to the dry adhesion strength of the laboratory formulated PF adhesive (3.4 ± 0.2 MPa).
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