{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T16:01:09Z","timestamp":1792166469611,"version":"4.4.0"},"reference-count":127,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2021,2,8]],"date-time":"2021-02-08T00:00:00Z","timestamp":1612742400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>The potential of using ground birch (Betula verrucosa Ehrh.) bark as an eco-friendly additive in urea-formaldehyde (UF) adhesives for plywood manufacturing was investigated in this work. Five-ply plywood panels were fabricated in the laboratory from beech (Fagus sylvatica L.) veneers bonded with UF adhesive formulations comprising three addition levels of birch bark (BB) as a filler (10%, 15%, and 20%). Two UF resin formulations filled with 10% and 20% wheat flour (WF) were used as reference samples. The mechanical properties (bending strength, modulus of elasticity and shear strength) of the laboratory-fabricated plywood panels, bonded with the addition of BB in the adhesive mixture, were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical strength of the plywood with the addition of BB in the adhesive mixture is acceptable and met the European standard requirements. Markedly, the positive effect of BB in the UF adhesive mixture on the reduction of formaldehyde emission from plywood panels was also confirmed. Initially, the most significant decrease in formaldehyde release (up to 14%) was measured for the plywood sample, produced with 15% BB. After four weeks, the decrease in formaldehyde was estimated up to 51% for the sample manufactured with 20% BB. The performed differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and derivative thermogravimetry (DTG), also confirmed the findings of the study. As this research demonstrated, BB as a waste or by-product of wood processing industry, can be efficiently utilized as an environmentally friendly, inexpensive alternative to WF as a filler in UF adhesive formulations for plywood manufacturing.<\/jats:p>","DOI":"10.3390\/polym13040511","type":"journal-article","created":{"date-parts":[[2021,2,10]],"date-time":"2021-02-10T04:33:46Z","timestamp":1612931626000},"page":"511","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":84,"title":["Utilization of Birch Bark as an Eco-Friendly Filler in Urea-Formaldehyde Adhesives for Plywood Manufacturing"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7983-4045","authenticated-orcid":false,"given":"Roman","family":"R\u00e9h","sequence":"first","affiliation":[{"name":"Faculty of Wood Sciences and Technology, Technical University in Zvolen, 960 01 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2385-5760","authenticated-orcid":false,"given":"\u013dubo\u0161","family":"Kri\u0161\u0165\u00e1k","sequence":"additional","affiliation":[{"name":"Faculty of Wood Sciences and Technology, Technical University in Zvolen, 960 01 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J\u00e1n","family":"Sedlia\u010dik","sequence":"additional","affiliation":[{"name":"Faculty of Wood Sciences and Technology, Technical University in Zvolen, 960 01 Zvolen, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4320-5247","authenticated-orcid":false,"given":"Pavlo","family":"Bekhta","sequence":"additional","affiliation":[{"name":"Department of Wood-Based Composites, Cellulose and Paper, Ukrainian National Forestry University, 79057 Lviv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8877-6206","authenticated-orcid":false,"given":"Monika","family":"Bo\u017eikov\u00e1","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Slovak University of Agriculture in Nitra, 949 76 Nitra, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniela","family":"Kunecov\u00e1","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Slovak University of Agriculture in Nitra, 949 76 Nitra, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1155-5039","authenticated-orcid":false,"given":"Vlasta","family":"Voz\u00e1rov\u00e1","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Slovak University of Agriculture in Nitra, 949 76 Nitra, Slovakia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2979-5893","authenticated-orcid":false,"given":"Eugenia Mariana","family":"Tudor","sequence":"additional","affiliation":[{"name":"Forest Products Technology and Timber Construction Department, Salzburg University of Applied Sciences, 5431 Kuchl, Austria"},{"name":"Faculty of Wood Engineering, Transilvania University of Brasov, 500036 Brasov, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3837-5380","authenticated-orcid":false,"given":"Petar","family":"Antov","sequence":"additional","affiliation":[{"name":"Faculty of Forest Industry, University of Forestry, 1797 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5111-8760","authenticated-orcid":false,"given":"Viktor","family":"Savov","sequence":"additional","affiliation":[{"name":"Faculty of Forest Industry, University of Forestry, 1797 Sofia, Bulgaria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,2,8]]},"reference":[{"key":"ref_1","unstructured":"Pizzi, A. 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