Wang Wei, Zheng Ke, Zhao Wenzheng, Zheng Shenglong, Wan Hui, Gao Jingran
Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products, Southwest Forestry University, Kunming 650224, China.
Key Laboratory of State Forestry and Grassland Administration on Highly-Efficient Utilization of Forestry Biomass Resources in Southwest China, Southwest Forestry University, Kunming 650224, China.
Polymers (Basel). 2024 Dec 7;16(23):3437. doi: 10.3390/polym16233437.
Tung oil pressing generates a substantial amount of tung cake waste rich in protein, which can be used to develop a novel wood protein adhesive. This study determined the optimal alkali treatment parameters based on NaOH concentration, reaction temperature, and reaction time. Potassium permanganate (KMnO) and methyl trimethoxy silane (MTMS) were then sequentially added for cross-linking modification to achieve the optimal preparation process for the tung cake protein adhesive. Bonding strength was tested on pressed boards, and various characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TG/TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), were used. The results indicated the following: (1) Optimal preparation conditions: The best preparation process for the adhesive involved 30% NaOH at 50 °C for 50 min, with the addition of 12% KMnO and 6% MTMS, meeting Class II plywood standards. (2) XRD and FTIR analyses revealed that carbohydrates in the tung cake oxidized and reacted with protein amino groups. The active groups in the protein cross-linked with MTMS, forming a spatial network structure, reducing hydrophilic groups, and enhancing water resistance. (3) TG/TGA and DSC showed that the thermal stability of the modified adhesive improved, thermogravimetric loss was reduced, and curing performance was enhanced. (4) SEM verified the adhesive's reaction mechanism, demonstrating that MTMS filled the protein structure unfolded by KMnO, forming a three-dimensional network and improving bonding strength. This study successfully developed a new, formaldehyde-free, environmentally friendly tung cake protein adhesive with excellent performance.
桐油压榨会产生大量富含蛋白质的桐饼废料，可用于开发新型木材蛋白胶粘剂。本研究基于氢氧化钠浓度、反应温度和反应时间确定了最佳碱处理参数。然后依次添加高锰酸钾（KMnO）和甲基三甲氧基硅烷（MTMS）进行交联改性，以实现桐饼蛋白胶粘剂的最佳制备工艺。对压制板材进行了粘结强度测试，并使用了各种表征技术，包括X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、热重分析（TG/TGA）、差示扫描量热法（DSC）和扫描电子显微镜（SEM）。结果表明：（1）最佳制备条件：胶粘剂的最佳制备工艺为在50℃下用30%的氢氧化钠处理50分钟，添加12%的KMnO和6%的MTMS，符合II类胶合板标准。（2）XRD和FTIR分析表明，桐饼中的碳水化合物氧化并与蛋白质氨基反应。蛋白质中的活性基团与MTMS交联，形成空间网络结构，减少亲水基团，提高耐水性。（3）TG/TGA和DSC表明，改性胶粘剂的热稳定性提高，热重损失降低，固化性能增强。（4）SEM验证了胶粘剂的反应机理，表明MTMS填充了由KMnO展开的蛋白质结构，形成三维网络并提高粘结强度。本研究成功开发出一种新型、无甲醛、环保且性能优异的桐饼蛋白胶粘剂。
