Réh Roman, Krišťák Ľuboš, Sedliačik Ján, Bekhta Pavlo, Božiková Monika, Kunecová Daniela, Vozárová Vlasta, Tudor Eugenia Mariana, Antov Petar, Savov Viktor
Faculty of Wood Sciences and Technology, Technical University in Zvolen, 960 01 Zvolen, Slovakia.
Department of Wood-Based Composites, Cellulose and Paper, Ukrainian National Forestry University, 79057 Lviv, Ukraine.
Polymers (Basel). 2021 Feb 8;13(4):511. doi: 10.3390/polym13040511.
The potential of using ground birch ( 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 ( 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.
本研究探讨了将桦树皮作为环保添加剂用于胶合板制造的脲醛（UF）胶粘剂中的潜力。在实验室中，用山毛榉单板制作了五层胶合板面板，这些单板用含有三种添加水平桦树皮（BB）作为填料（10%、15%和20%）的UF胶粘剂配方进行粘结。两种分别填充10%和20%小麦粉（WF）的UF树脂配方用作参考样品。对在胶粘剂混合物中添加了BB粘结而成的实验室制作胶合板面板的力学性能（弯曲强度、弹性模量和剪切强度）进行了评估，并与欧洲标准要求（EN 310和EN 314-2）进行了比较。在胶粘剂混合物中添加了BB的胶合板的力学强度是可接受的，符合欧洲标准要求。值得注意的是，还证实了BB在UF胶粘剂混合物中对降低胶合板面板甲醛释放量的积极作用。最初，对于添加15%BB生产的胶合板样品，测得甲醛释放量下降最为显著（高达14%）。四周后，对于添加20%BB制造的样品，甲醛下降估计高达51%。所进行的差示扫描量热法（DSC）、热重分析（TGA）和微商热重法（DTG）也证实了该研究的结果。正如本研究所表明的，桦树皮作为木材加工业的废料或副产品，可以有效地作为一种环保、廉价的替代品，替代小麦粉作为胶合板制造中UF胶粘剂配方的填料。
