Feather Keratin Binder for Particleboards: A Sustainable Alternative to Urea-Formaldehyde and Food-Based Protein Adhesives

Abstract

This study evaluates keratin as a formaldehyde-free adhesive for three-layer particleboards for EN 312 (2010) P1-type by developing a sustainable alternative to urea-formaldehyde (UF) resins while decreasing reliance on food-derived protein adhesives. Keratin was extracted from duck feathers using ultrasound-assisted alkaline hydrolysis. Particleboards were made with keratin-based adhesives and compared to panels bonded with UF resin and food protein isolates (casein, pea, and soybean). Resination was set at 10% for the core layer and 12% for the face layers. Protein adhesives were activated with NaOH. Mechanical performance was assessed by measuring modulus of rupture (MOR), modulus of elasticity (MOE), internal bond strength (IB), and screw withdrawal resistance (SWR), along with thickness swelling (TS) and water absorption (WA). The protein-bonded panels exhibited higher face-layer densities than UF, leading to improved stiffness and strength. Keratin-bonded boards achieved an MOR of 12 N·mm^-2, an MOE above 3000 N·mm^-2, and an SWR of 139 N·mm^-2, surpassing UF performance and meeting EN 312 P1 (2010) requirements. Results demonstrate the potential of feather keratin as a scalable, green, and cost-effective adhesive for dry-use particleboards. This approach promotes renewable adhesive systems, aligning with current regulatory trends toward formaldehyde-free materials and circular bioeconomy strategies.