Urea’s Impact on Curing Dynamics, Resin Structure, and Properties of Urea-Formaldehyde Adhesives
Keywords:
Particleboard, urea-formaldehyde resin, curing agents, modifier-curing agentAbstract
The curing of urea-formaldehyde resin in the presence of urea used to reduce the formaldehyde content in particleboards was researched. Free urea was added into the adhesive with different amounts of latent curing agent (1 and 3% ammonium sulfate based on dry resin); a urea which is part of the modifiers-curing agents (products of the interaction of citric acid, urea and ammonia) was also studied separately. Based on the results of differential scanning calorimetry, solid-state NMR 13C of the cured resin and tests of model particleboards, it was suggested that the effect of urea is significantly influenced by the pH value of the adhesive before and during curing. At a relatively high pH value (3.50-3.70 after curing at ammonium sulfate content of 1%), urea acts as a classical scavenger, that is, it chemically interacts with formaldehyde to form harmless products. At a reduced pH value (3.00-3.10 after curing at ammonium sulfate content of 3%), urea reacts with resin components (methylolureas and UF oligomers mainly) that is, it participates in the curing of the adhesive. Tests of model samples of particleboards have shown that the mechanism of including urea into the structures of the curing resin is less effective for reducing toxicity than its action as a classical scavenger; at the same time, the formaldehyde content in particleboards with 3% ammonium sulfate and urea is lower in absolute values due to the useful effect of the curing agent. Modifiers-curing agents provide a low pH value of the binder before curing (3.72-4.51 with a content of modifiers-curing agents of 5%), urea in their composition is also involved in curing (according to solid-state NMR data).
References
George I. Mantanis, Eleftheria Th. Athanassiadou, Marius C. Barbu, Kris Wijnendaele (2017) Adhesive systems used in the European particleboard, MDF and OSB industries. https://doi.org/10.1080/17480272.2017.1396622
A. Pizzi, A. N. Papadopoulos, F. Policardi (2020) Wood Composites and Their Polymer Binders. 12(5), 1115. https://doi.org/10.3390/polym12051115
Lubos Kristak, Petar Antov, Pavlo Bekhta, Muhammad Adly Rahandi Lubis, Apri Heri Iswanto, Roman Reh, Jan Sedliacik, Viktor Savov, Hamid R. Taghiyari, Antonios N. Papadopoulos, Antonio Pizzi, Aleksander Hejna (2022) Recent progress in ultra-low formaldehyde emitting adhesive systems and formaldehyde scavengers in wood-based panels: a review. https://doi.org/10.1080/17480272.2022.2056080
P. Antov, V. Savov, N. Neykov (2020) Reduction of formaldehyde emission from engineered wood panels by formaldehyde scavengers – a review.
H. Wang, M. Cao, T. Li, L. Yang, Z. Duan, X. Zhou, G. Du (2018) Characterization of the Low Molar Ratio Urea–Formaldehyde Resin with ^{13} C NMR and ESI–MS: Negative Effects of the Post-Added Urea on the Urea–Formaldehyde Polymers. 10(6), 602. https://doi.org/10.3390/polym10060602
S. N. Vyunkov (2019) The effect of urea on the curing of urea formaldehyde resins. 226, 155–161. https://doi.org/10.21266/2079-4304.2019.226.155-16.1
Cheng Xing, S. Y. Zhang, James Deng, Siqun Wang (2007) Urea–formaldehyde-resin gel time as affected by the pH value, solid content, and catalyst. 103(3), 1566–1569. https://doi.org/10.1002/app.25343
Mohsen Khonakdar Dazmiri, Mohammad Valizadeh Kiamahalleh, Ali Dorieh, Antonio Pizzi (2019) Effect of the initial F/U molar ratio in urea-formaldehyde resins synthesis and its influence on the performance of medium density fiberboard bonded with them. 95, 102440. https://doi.org/10.1016/j.ijadhadh.2019.102440
Ali Dorieh, Nosratollah Mahmoodi, Manouchehr Mamaghani, Antonio Pizzi, Massoud Mohammadi Zeydi (2019) Comparison of the properties of urea-formaldehyde resins by the use of formalin or urea formaldehyde condensates. 32(23), 1–15. https://doi.org/10.1080/01694243.2018.1492780
Arif Nuryawan, Byung-Dae Park, Adya P. Singh (2014) Comparison of thermal curing behavior of liquid and solid urea–formaldehyde resins with different formaldehyde/urea mole ratios. 118, 397–404. https://doi.org/10.1007/s10973-014-3946-5
Byung-Dae Park, Eun-Chang Kang, Jong-Young Park (2014) Thermal Curing Behavior of Modified Urea-Formaldehyde Resin Adhesives with Two Formaldehyde Scavengers and Their Influence on Adhesion Performance. 118(1). https://doi.org/10.1007/s10973-014-3946-5
S. Boran, M. Usta, E. Gümüşkaya (2011) Decreasing formaldehyde emission from medium density fiberboard panels produced by adding different amine compounds to urea formaldehyde resin. 31, 674–678. https://doi.org/10.1016/j.ijadhadh.2011.06.011
A. İstek, İ. Özlüsoylu, S. Bakar, E. Öz (2018) Tutkal Çözeltisine Üre İlavesinin Formaldehit Emisyonu ve Levha Özelliklerine Etkisi. 824–830.
H. Yang, H. Wang, G. Du, K. Ni, Y. Wu, H. Su, W. Gao, X. Tan, Z. Yang, L. Yang (2023) Ureido Hyperbranched Polymer Modified Urea-Formaldehyde Resin as High-Performance Particleboard Adhesive. 16(11), 4021. https://doi.org/10.3390/ma16114021
Daria A. Perminova, Victor S. Malkov, Irina A. Kurzina, Tatiana B. Babushkina (2015) Wood composite materials based on glycoluril-modified urea-formaldehyde resins. 238-241. https://doi.org/10.17223/15617793/391/38
R. Paleckiene, A. Sviklas, R. Slinksiene (2005) Reaction of Urea with Citric Acid. 78(10), 1651–1655. https://doi.org/10.1007/s11167-005-0579-2
D.V. Ivanov, S.V. Shevchenko, M.A. Ekaterincheva (2019) The hardener of urea-formaldehyde resin, which reduce toxicity of wood board. 229, 215–230. https://doi.org/10.21266/2079-4304.2019.229.215-230
Roffael E. (1993) Formaldehyde release from particleboard and other wood based panels. 281 p..
E. Kantieva, L. Ponomarenko The effect of curing agents to urea-formaldehyde resins physico-chemical properties. 94–98.
K. Siimer, T. Kaljuvee, P. Christjanson (2003) Thermal behavior of urea-formaldehyde resins during curing. 72, 607–617. https://doi.org/10.1023/A:1024590019244
T. Zorba, E. Papadopoulou, A. Hatjiissaak, K. M. Paraskevopoulos, K. Chrissafis (2008) Ureaformaldehyde resins characterized by thermal analysis and FTIR method. 92(1). https://doi.org/10.1007/s10973-007-8731-2
Z. Ding, Z. Ding, T. Ma, H. Zhang (2020) Condensation reaction and crystallization of urea-formaldehyde resin during the curing process. 15(2), 2924–2936. https://doi.org/10.15376/biores.15.2.2924-2936
A. Šebenik, U. Osredkar, Majda Zigon, I. Vizovišek (2003) Study of the reaction between Urea and Formaldehyde by DSC and {}^{13} C NMR Spectroscopy. 102(1), 81–85. https://doi.org/10.1002/apmc.1982.051020109
Mlađan Popović, Jovan Miljkovic, Jaroslava Budinski-Simendic, J. Pavličević, Ivan Ristić (2011) Curing characteristics of low emission urea-formaldehyde adhesive in the presence of wood. 56(4), 589–600.
Chang Liu, Jianlin Luo, Xiaona Li, Qiang Gao, Jianzhang Li (2018) Effects of Compounded Curing Agents on Properties and Performance of Urea Formaldehyde Resin. 26(6), 158–165. https://doi.org/10.1007/s10924-016-0913-1
Taohong Li, Jiankun Liang, Ming Cao, Xiaoshen Guo, Xiaoguang Xie, Guanben Du (2016) Re-elucidation of the acid-catalyzed urea-formaldehyde reactions: A theoretical and {}^{13} C-NMR study. 133(48). https://doi.org/10.1002/app.44339
S.N. Viunkov, V.V. Vasilyev (2023) Modification of the hardener of urea-formaldehyde resins with a low molar ratio of formaldehyde to urea. 243, 284–296. https://doi.org/10.21266/2079-4304.2023.243.284-296
N. A. Costa, J. Pereira, J. Ferra, P. Cruz, J. Martins, F. D. Magalhães, A. Mendes, L. H. Carvalho (2014) Formaldehyde emission in wood based panels: Effect of curing reactions. 5(3), 146–160. https://doi.org/10.1179/2042645314Y.0000000070
N. A. Costa, J. Pereira, J. Martins, J. Ferra, Paulo Cruz, F. D. Magalhães, A. Mendes, L. H. Carvalho (2012) Alternative to latent catalysts for curing UF resins used in the production of low formaldehyde emission wood-based panels. 33, 56–60. https://doi.org/10.1016/j.ijadhadh.2011.11.003
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