Abstract The aim of this work was to improve the properties of plywood panels bonded with urea-lignin-glyoxal (ULG) resin by small addition of epoxy resin. For this reason, various contents (1, 3 and 5% on resin solids) of an epoxy resin were added to the prepared ULG resin. The structural, thermal and physicochemical properties of the resins prepared as well as the water absorption and wet and dry shear strength of the plywood panels bonded with them were measured according to standard methods. The results showed that the addition of an epoxy resin significantly accelerated the gel time and increased the ULG resin viscosity, density and solids content. The cross-linking structure in the cured ULG resin with the epoxy resin was confirmed by FTIR analysis. The curing temperature of the ULG resin also decreases by addition of the epoxy resin as shown by differential scanning calorimetry (DSC). As a consequence, the plywood panels bonded with ULG resins containing any amount of the epoxy resin presented a better dimensional stability than those bonded with the control resin. The dry and wet tensile shear strength of plywood panels bonded with ULG resins indicate that they could be significantly improved by increasing the percentage of the epoxy resin added.

中文翻译：

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少量添加环氧树脂改善尿素-木质素-乙二醛树脂作为木材粘合剂的性能

摘要 这项工作的目的是通过少量添加环氧树脂来改善与尿素-木质素-乙二醛 (ULG) 树脂粘合的胶合板的性能。为此，将各种含量的环氧树脂（树脂固体的 1、3 和 5%）加入到制备的 ULG 树脂中。根据标准方法测量制备的树脂的结构、热和物理化学性质以及与其粘合的胶合板的吸水率和干湿剪切强度。结果表明，环氧树脂的加入显着加快了凝胶时间，并增加了 ULG 树脂的粘度、密度和固含量。固化的 ULG 树脂与环氧树脂的交联结构通过 FTIR 分析得到证实。如差示扫描量热法 (DSC) 所示，ULG 树脂的固化温度也随着环氧树脂的加入而降低。因此，与含有任意量环氧树脂的 ULG 树脂粘合的胶合板比那些与对照树脂粘合的胶合板具有更好的尺寸稳定性。用 ULG 树脂粘合的胶合板的干和湿拉伸剪切强度表明它们可以通过增加环氧树脂的添加百分比得到显着提高。