Simultaneous bond degradation and bond formation during phenol-formaldehyde curing with wood

Abstract

Bonding of wood using phenol–formaldehyde adhesive develops highly durable bonds. Phenol– formaldehyde is believed to form primary bonds with wood cell wall polymers (e.g., lignin). However, it is unclear how this adhesive interacts and bonds to lignin. Through wood solubilisation methodologies, earlywood and latewood bonded assemblies were characterized using two-dimensional ¹H–¹³C solution-state nuclear magnetic resonance spectroscopy so that chemical modification of the wood cell wall polymers, after phenol–formaldehyde resol curing, could be elucidated. The results showed a marked depletion in native lignin and polysaccharide linkages via alkaline hydrolysis. What was also found was formation of methylene bridges between phenol–formaldehyde moieties and lignin, suggesting that bond degradation and bond formation occur at the same time during PF curing with wood.

Citation

Yelle, Daniel J.; Ralph, John. 2016. Simultaneous bond degradation and bond formation during phenol-formaldehyde curing with wood. In: WTCE 2016, World Conference on Timber Engineering; 22-25 August . Vienna, Austria. 7 pp.