Abstract
Phenol formaldehyde (PF) resin is a well-tried adhesive for manufacturing laminated veneer lumber (LVL). PF has a high bonding strength, good cold pressing property and contributes a lot to the high production efficiency of LVL. In the present paper, PFs were synthesized at three different alkaline condition levels with a molar formaldehyde to phenol (F/P) ratio of 2.25. The bonding strength of PFs was not influenced by the alkalinity. Compared with PFs synthesized under alkalinity of 1 and 4%, PF with 8% alkalinity formed a resin with a high mole mass (MM), uniform mole mass distribution (MMD) and a high cross-linking density. With PF8%, the cold pressing property could be shortened from 30 to 12 min in the winter time. Cured PF8% had a higher cross-linking density than PF1% and PF4%. PF8% has a high potential for industrial production of LVL.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: This work was supported by the National Natural Science Foundation of China (Funder Id: 10.13039/501100001809, Grant No. 31370567) and Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the Doctorate Fellowship Foundation of Nanjing Forestry University.
Employment or leadership: None declared.
Honorarium: None declared.
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