Chen Yaoxing, Rao Yongjing, Liu Peng, Wu Linlin, Zhang Guojie, Zhang Jianguo, Xie Fengwei
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, China.
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou Higher Education Mega Center, Guangzhou, Guangdong 510006, China.
Carbohydr Polym. 2024 Sep 1;339:122247. doi: 10.1016/j.carbpol.2024.122247. Epub 2024 May 8.
The escalating demand for environmentally sustainable and cost-effective adhesives in the wood processing and manufacturing sector has prompted exploration into innovative solutions. This study introduces a novel gel adhesive composed of chemically unmodified high-amylose starch (G70, with 68 % amylose content) with a minimal proportion of urea-formaldehyde (UF) (UF/starch = 1:10, w/w). This G70/UF gel demonstrates remarkable adhesive capabilities for wooden boards under both dry conditions (with a shear stress of 4.13 ± 0.12 MPa) and wet conditions (with a shear strength of 0.93 ± 0.07 MPa after 2 h of water soaking). The study unveils that the elevated amylose content in the starch, coupled with a meticulously controlled isothermal process during bonding, is crucial for these enhancements. Specifically, the robust cohesion of amylose chains expedites phase separation between starch and UF, while the isothermal process facilitates the migration and enrichment of UF molecules at the gel-board and gel-air interfaces. Lacking these mechanisms, conventional amylopectin-rich starch/UF gels (27 % amylose content) show minimal improvement. Moreover, the G70/UF gel showcases exceptional fire retardancy. In all, the G70/UF gel presents a promising alternative for plywood production, reducing reliance on unhealthy UF resin while offering satisfactory bonding resistance in diverse conditions and superior flame retardancy.
木材加工和制造业对环境可持续且经济高效的粘合剂需求不断增加，促使人们探索创新解决方案。本研究介绍了一种新型凝胶粘合剂，它由化学未改性的高直链淀粉（G70，直链淀粉含量为68%）与最低比例的脲醛（UF）（UF/淀粉 = 1:10，w/w）组成。这种G70/UF凝胶在干燥条件下（剪切应力为4.13±0.12 MPa）和潮湿条件下（水浸泡2小时后剪切强度为0.93±0.07 MPa）对木板都具有显著的粘合能力。该研究表明，淀粉中较高的直链淀粉含量，加上粘合过程中精心控制的等温过程，对这些性能提升至关重要。具体而言，直链淀粉链的强大内聚力加速了淀粉与UF之间的相分离，而等温过程则促进了UF分子在凝胶-木板和凝胶-空气界面的迁移和富集。缺乏这些机制，传统的富含支链淀粉的淀粉/UF凝胶（直链淀粉含量27%）几乎没有改善。此外，G70/UF凝胶还具有出色的阻燃性。总之，G70/UF凝胶为胶合板生产提供了一种有前景的替代品，减少了对不健康的UF树脂的依赖，同时在不同条件下提供了令人满意的粘合抗性和卓越的阻燃性。
