Sustainable adhesives are becoming increasingly important, especially in applications where petrochemical resins containing problematic substances such as formaldehyde still dominate. Our latest study now shows that chitosan-based wood adhesives are a promising bio-based alternative. Chitosan is derived from chitin, a natural polymer found, among other sources, in the shells of crustaceans and generated in large quantities as a by-product of the food industry.
Two fully bio-based adhesive systems were investigated: chitosan itaconate and chitosan maleate. Both are based on renewable raw materials and were specifically developed for wood bonding. What is particularly interesting is that the acids used not only solubilize the chitosan, but also enable curing into a stable network. Both acids can be obtained via biofermentation, making the adhesive system entirely bio-based.
The results are remarkable: in the dry state, both adhesives met the requirements of DIN EN 12765 class C1 and exhibited so-called cohesive wood failure. This means that under mechanical stress, it was not the adhesive bond that failed, but the wood itself. Chitosan itaconate, in particular, also performed well under wet conditions: after treatment in boiling water, its bond strength remained at 2.7 N/mm², close to the demanding C4 class.
Chitosan itaconate is therefore a promising candidate for wood bonding applications requiring moderate moisture resistance, such as interior construction or semi-exposed uses. Chitosan maleate also showed good dry adhesion, but lost significant stability upon contact with water.
In conclusion, bio-based wood adhesives made from chitosan are far more than a niche concept. Chitosan itaconate in particular combines renewable raw materials with convincing adhesive performance and could represent an important step toward more environmentally friendly materials in the wood industry.
N. Münstermann, O. Weichold
Chitosan-itaconate and chitosan-maleate as fully bio-based sustainable wood adhesives
International Journal of Adhesion and Adhesives, 2026, 149, 104327 https://doi.org/10.1016/j.ijadhadh.2026.104327
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