Introduction of aldehyde groups into surface of pine bark via Cannizzaro reaction to improve Urea-formaldehyde resin properties.

Pine bark, a natural and renewable forest residue, was modified using a simple interfacial solid-phase chemical method to design a highly chemically reactive additive for urea-formaldehyde (UF) resin. The modification introduced carbonyl groups onto the bark surface during the glyoxal reaction at the bark-solid interface. Thermal properties, including curing temperatures, of UF, UFB, and UFGB were evaluated using DSC and DMA. Glyoxal modification of bark significantly influenced these properties, facilitating the crosslinking and curing of adhesives. Notably, plywood bonded with UFGB resin released approximately half as much formaldehyde (52.89 % less) compared to plywood bonded with UF resin, reducing from 1.38 to 0.65 mg/L. Additionally, the wet shear strength of plywood increased by 197.3 %, from 0.37 MPa to 1.10 MPa, exceeding the minimum requirement (0.7 MPa) defined by the China national standard (GB/T 17657–2013). The study presents a compelling case for the utilization of glyoxal-modified pine bark as a filler in UF adhesive for plywood manufacturing. The demonstrated improvements in plywood properties and formaldehyde emissions, along with the environmentally friendly nature of the approach, make it a promising avenue for sustainable plywood production. Further investigations into the underlying mechanisms and long-term performance are encouraged to solidify the potential of this technology. [Display omitted] • Reduced formaldehyde emissions: Plywood bonded with a UF resin containing glyoxal-modified pine bark as a reactive additive released nearly 53 % less formaldehyde , a major health concern. • Enhanced strength: The wet shear strength of the plywood increased by almost 200 % , exceeding national standards. • Sustainable approach: Utilizing a natural waste product and a simple modification process makes this method environmentally friendly. • Cost-effective: The modified bark powder can be easily incorporated into existing production lines, minimizing additional costs. [ABSTRACT FROM AUTHOR]