Structure and Strength Properties of Plywood with Modified Binder. P. 157–170

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UDС

674.419.32

DOI:

10.37482/0536-1036-2026-4-157-170

Abstract

The research is aimed at improving the mechanical properties of plywood produced at a pressing temperature of 105 °C using phenol-formaldehyde resin modified with copper-containing additives or resorcin. The 5-layer waterproof plywood is made of 1.5 mm thick birch veneer and a phenol-formaldehyde resin binder. Copper acetate, resorcin, and copper resorcinate were used as modifiers (10 % aqueous solutions). We evaluated the strength of plywood under static bending and its strength when shearing along the adhesive layer after boiling. IR spectra of the binder and the plywood were obtained. The number of hydroxyl and hydroxymethyl groups decreases, and the hydrolytic stability of the binder increases due to the formation of coordinate bonds between the copper ion and the hydroxyl groups of the binder when the resin is modified with copper acetate and copper resorcinate. The number of hydroxyl groups remains virtually unchanged, but the number of –CH2 groups increases when the resin is modified with resorcin. Modification of the resin with copper resorcinate during low-temperature pressing resulted in a 52.2 % increase in shearing strength along the adhesive layer, with resorcin – a 70.0 % increase, and with copper acetate – a 78.8 % increase, compared to the values for samples made with phenol-formaldehyde resin. The static bending strength of plywood is the highest for the samples containing copper acetate and resorcin; it is higher than that of the samples produced at 120 °C. The use of copper acetate and resorcin for modification at 105 °C provides comparable mechanical properties of plywood. Since copper acetate is less expensive than resorcin, the use of a copper acetate-modified phenol-formaldehyde resin is recommended for industrial applications requiring low-temperature pressing. Lowering the pressing temperature will reduce the costs associated with the production of water-resistant plywood.

Funding: The research was carried out as part of research project No. 24-29-20157 with financial support from the Russian Science Foundation and the Administration of the Kostroma Region.

Acknowledgments: We used the equipment of the Testing Laboratory of the Federal State Unitary Enterprise “Central Research Institute of Chemistry and Mechanics” (Moscow). The results were verified at the Wood-Based Panels and Plywood Testing Laboratory of the OOO Lessertika in the city of Balabanovo.

Authors

Aleksandr А. Fedotov*, Candidate of Engineering, Assoc. Prof.; ResearcherID: R-1155-2018, ORCID: https://orcid.org/0000-0002-3668-899X
Tatiana N. Vakhnina, Candidate of Engineering, Assoc. Prof.; ResearcherID: R-1116-2018, ORCID: https://orcid.org/0000-0002-7201-5979
Irina V. Susoeva, Doctor of Engineering, Assoc. Prof.; ResearcherID: R-1053-2018, ORCID: https://orcid.org/0000-0002-7295-8934
Andrey А. Titunin, Doctor of Engineering, Assoc. Prof.; ResearcherID: W-5121-2017, ORCID: https://orcid.org/0000-0002-0953-0898

Affiliation

Kostroma State University, Kostroma, Russia; aafedotoff@yandex.ru*, t_vachnina@mail.ru, i.susoeva@yandex.ru, a_titunin@kosgos.ru

Keywords

waterproof plywood, phenol-formaldehyde binder, modifiers, hot pressing, mechanical properties, IR spectra

For citation

Fedotov A.A., Vakhnina T.N., Susoeva I.V., Titunin A.A. Structure and Strength Properties of Plywood with Modified Binder. Lesnoy Zhurnal = Russian Forestry Journal, 2026, no. 4, pp. 157–170. (In Russ.). https://doi.org/10.37482/0536-1036-2026-4-157-170

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