High-strength particleboards from fast-growing plant residues and food-industry by-products using chitosan-itaconate as orthogonal binder platform

This study demonstrates a simple and effective route to convert agricultural residues and food-processing by-products into high-performance composite bio-boards. Fast-growing plants such as hemp shives, miscanthus and Japanese knotweed were combined with a chitosan-based binder derived from food industry residues and itaconic acid. A common challenge for many chitosan-bound particle boards is their low strength and water stability. In the present case, polymerisation of itaconic acid during hot-pressing generated dense and water-insoluble networks, resulting in boards with flexural strengths up to 76.5 N∙mm⁻² and moduli of elasticity up to 6700 N∙mm⁻², values exceeding those of commercial hardboards and approaching those of solid spruce wood. Despite water uptake of about 16 wt% after 48 h, thickness swelling after 24 h remained within specifications for dry-use hardboards, and the boards maintained their integrity during prolonged immersion. Biodegradation tests confirmed full compostability, germination assays showed no ecotoxic effects, and an indicative UL-94 HB screening suggested self-extinguishing behaviour. Beyond their mechanical and environmental performance, the boards can be produced from a wide variety of locally available plant residues, enabling regionally adapted value chains and reducing transport-related emissions. In addition, the fast-growing grasses sequester large amounts of CO 2 while the binder valorises food industry residues that would otherwise be discarded. • Bio-based chitosan-itaconate binder enables formaldehyde-free particleboards. • Orthogonal reactivity forms strong interpolyelectrolyte complexes. • Bending strength up to 77 N·mm⁻², surpassing spruce wood and commercial particleboards. • Compatible with various lignocellulosic wastes, demonstrated mainly with Miscanthus.