Modification of Phenol Formaldehyde Resins with Wood-Pyrolysis Liquid

One of the directions for improving the production of adhesive materials is the modification of phenol formaldehyde resins. Utilizing the waste and intermediate products from wood-processing industries, particularly in the form of wood-pyrolysis liquid, will deepen the process of comprehensive resource utilization. A body of research lays the groundwork for further developments and targeted regulation of the physicochemical properties of wood-pyrolysis liquid-modified phenol formaldehyde adhesive. The experimental results clearly show that the addition of wood-pyrolysis liquid in various fractional phases (up to 15–20%) significantly increases the delamination and bending strength of birch plywood samples beyond the standard. This is due to the resinous and fatty acids in the wood-pyrolysis liquid reacting with formaldehyde. The resinous and fatty acids integrate into the polymer molecule of the phenol formaldehyde resin, forming a spatially branched structure, leading to the formation of a polymer with a new set of properties. In the interaction mechanism of wood-pyrolysis-liquid-modified phenol formaldehyde adhesive, there is a sequential increase in the molecular weight of substances and, consequently, the depth of penetration.