University of Tehran Forest and Wood Products 5052-2008 77 3 2024 11 21 Performance of beech wood modified with dimethylol dihydroxyethylene urea (DMDHEU) against accelerated weathering Performance of beech wood modified with dimethylol dihydroxyethylene urea (DMDHEU) against accelerated weathering 313 326 99814 10.22059/jfwp.2024.381075.1309 FA Zahra Rezaei Department of Wood and Paper Science and Technology, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. Asghar Tarmian Department of Wood and Paper Science and Technology, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. Aisona Talaei Department of Wood Science Engineering, Faculty of Materials Engineering and Interdisciplinary Science, Shahid Rajaee Teacher Training University, Tehran, Iran. Journal Article 2024 08 20 The performance of beech wood modified with methylolated dimethylol dihydroxyethylene urea (mDMDHEU), with low formaldehyde emission, against weathering was investigated. Methylolated dimethylol dihydroxyethylene urea, at a concentration of 30%, and MgCl₂ as a catalyst at 5% by weight were used. After impregnation of the wood samples via the vacuum-pressure process, the samples were cured under superheated steam conditions (100°C for 36 hours) and in an oven (120°C for 24 hours). The weathering resistance of the samples was evaluated under accelerated weathering conditions for 750 hours. The results showed that the weight percent gain (%WPG) was higher in the oven curing method due to the higher treatment temperature; however, the superheated steam curing method showed better performance against weathering. The highest water absorption and swelling occurred in the control sample, while the lowest was observed in the oven-cured sample. The results indicated that the higher treatment temperature led to a further decrease in water absorption and an increase in dimensional stability. FTIR spectroscopy after weathering showed a reduction in the peak of aromatic rings in the modified samples, indicating that lignin was not effectively protected against weathering in any of the treatments. Compared to oven curing, curing with superheated steam resulted in greater water repellency of the surface and reduced changes in color and surface morphology caused by weathering. The performance of beech wood modified with methylolated dimethylol dihydroxyethylene urea (mDMDHEU), with low formaldehyde emission, against weathering was investigated. Methylolated dimethylol dihydroxyethylene urea, at a concentration of 30%, and MgCl₂ as a catalyst at 5% by weight were used. After impregnation of the wood samples via the vacuum-pressure process, the samples were cured under superheated steam conditions (100°C for 36 hours) and in an oven (120°C for 24 hours). The weathering resistance of the samples was evaluated under accelerated weathering conditions for 750 hours. The results showed that the weight percent gain (%WPG) was higher in the oven curing method due to the higher treatment temperature; however, the superheated steam curing method showed better performance against weathering. The highest water absorption and swelling occurred in the control sample, while the lowest was observed in the oven-cured sample. The results indicated that the higher treatment temperature led to a further decrease in water absorption and an increase in dimensional stability. FTIR spectroscopy after weathering showed a reduction in the peak of aromatic rings in the modified samples, indicating that lignin was not effectively protected against weathering in any of the treatments. Compared to oven curing, curing with superheated steam resulted in greater water repellency of the surface and reduced changes in color and surface morphology caused by weathering. https://jfwp.ut.ac.ir/article_99814_4fe87b106825fc7f3510efb7580e47e8.pdf