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Sustainable chitosan–rosin adhesives: Strong, flame-retardant and biodegradable alternatives for wood panels
A Chinese research team has developed an eco-friendly wood adhesive based on chitosan and modified rosin acid. The formulation achieves high mechanical strength, flame retardancy and rapid biodegradability, offering a viable alternative to formaldehyde-based resins.
Chitosan, a renewable biopolymer derived from chitin, offers excellent environmental compatibility but has so far been limited in adhesive applications due to low strength and high water uptake. A team led by Qi Huang has now developed a multifunctional bio-adhesive (CS-BA-ERA) that overcomes these drawbacks by combining chitosan (CS), boric acid (BA) and epoxidised rosin acid (ERA) into a reinforced network.
The adhesive delivered strong performance: plywood achieved a dry shear strength of 2.71 MPa and a wet shear strength of 1.92 MPa. Particleboards bonded with CS-BA-ERA reached a flexural strength of 21.00 MPa, an internal bond strength of 0.85 MPa and only 11.06 % thickness swelling after 24 hours of water immersion. Molecular dynamics simulations confirmed that synergistic crosslinking improved interfacial adhesion and overall network stability.
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Flame retardant, biodegradable and eco-friendly
Beyond strength, the adhesive provides excellent flame retardancy, achieving a limiting oxygen index of 81.10 % and a char residue of 43.84 % at 599.60 °C. Compared with conventional melamine–formaldehyde and phenol–formaldehyde resins, it shows a significantly lower environmental impact and undergoes over 95 % biodegradation within 15 days. This research highlights a renewable and biodegradable alternative to petroleum-based adhesives for wood panel production.
Source: Huang, Q. et al. Nature-derived adhesives based on chitosan and rosin acid with high strength, flame retardancy, and environmental friendliness. Green Chem. 39, (2025).
