Enhancing adhesive properties with unmodified and phosphate-modified chitin in particleboard production.

This research modifies chitin (CT) from shrimp shell residues into phosphorylated chitin (PCT) using diammonium hydrogen phosphate and urea. The study evaluates the effectiveness of PCT as a sustainable additive for urea formaldehyde (UF)-based wood adhesives. Structural and thermal analyses of CT and PCT were conducted using SEM-EDX, ATR-FTIR, XRD, TGA/DTG, conductometric titration, and Degree of Substitution measurements. Particleboard (PB) samples were fabricated using UF adhesives blended with 4-10 wt% CT or PCT. Results showed that 6 wt% PCT with UF adhesive as optimal formulation which enhances dry internal bond (0.64 MPa), modulus of elasticity (3627 MPa), modulus of rupture (24 MPa), and surface soundness (1.83 MPa), respectively, over the PBs bonded only with UF resin (0.46 MPa, 2589, MPa,16 MPa and 1.59 MPa). Moreover, when 8 wt% of PCT and CT reduced formaldehyde emissions to 2.84 and 3.88 mg/100 g, respectively, compared to unmodified UF adhesive (4.62 mg/100 g). Besides, the addition of 6 wt% PCT exhibited a decrease in the values Thickness Swelling and Water Adsorption by 18.57 % and 14.35 % after 2 h and 24 h, respectively. The findings highlight PCT-enhanced UF adhesives as an eco-friendly alternative for PB manufacturing, offering superior mechanical performance and reduced environmental footprint.