Soy-based adhesives inherently possess low water resistance and brittleness, which limit their application on plywood fabrication. This investigation involves using a long chain cross-linker, neopentyl glycol diglycidyl ether (NGDE), to produce an intrinsic toughening effect to reduce the brittleness and improve the water resistance of a soybean meal⁻based adhesive. The solids content, viscosity, functional groups, fracture surface micrographs, and thermal stability of the adhesives were measured. Three-layer plywood was fabricated using the resultant adhesive, and the tensile shear strength of the plywood was measured. All adhesive properties were compared with a soybean meal/polyamidoamine-epichlorohydrin (PAE) adhesive and commercial melamine urea formaldehyde resin. The results showed that adding 6 g NGDE improved the water resistance of the soybean meal-based adhesive by 12.5%. This improvement is attributed to the following reasons: (1) a dense cross-linked network is formed by the chemical reaction between NGDE and protein molecules; (2) the toughness of the adhesive increases and a smooth and homogeneous fracture surface is created, which effectively prevents moisture intrusion; (3) the addition of NGDE increases the thermostability of the cured adhesive. The tensile shear strength of the plywood bonded with the soybean meal-based adhesive with 6 g NGDE was 286.2% higher than that without NGDE and attained 1.12 MPa, which was attributed to the reduction in the adhesive's viscosity, and the improvement in the water resistance and toughness of the adhesive. The tensile shear strength of the plywood bonded with 6 g NGDE was 19.1% higher than that with 6 g PAE and was similar to the MUF resin, which validated the novel adhesive being suitable for use as an industrial plywood adhesive.

中文翻译：

---

新戊二醇二缩水甘油醚增强的新型柔性大豆基粘合剂：性能和应用。

大豆基粘合剂本身具有低耐水性和脆性，这限制了它们在胶合板制造中的应用。这项研究涉及使用长链交联剂新戊二醇二缩水甘油醚（NGDE）来产生内在的增韧效果，从而降低豆粕基粘合剂的脆性并提高耐水性。测量了粘合剂的固含量、粘度、官能团、断裂表面显微照片和热稳定性。使用所得粘合剂制造三层胶合板，并测量胶合板的拉伸剪切强度。所有粘合性能均与豆粕/聚酰胺-环氧氯丙烷 (PAE) 粘合剂和商用三聚氰胺脲甲醛树脂进行了比较。结果表明，添加6 g NGDE使豆粕胶的耐水性提高了12.5%。这种改进归因于以下原因：（1）NGDE与蛋白质分子之间的化学反应形成致密的交联网络；(2)胶粘剂的韧性增加，断裂面光滑、均匀，有效防止水分侵入；(3)NGDE的添加提高了固化胶的热稳定性。使用添加 6 g NGDE 的豆粕胶粘剂粘合的胶合板的拉伸剪切强度比未添加 NGDE 的胶合板高 286.2%，达到 1.12 MPa，这归因于粘合剂粘度的降低和耐水性的提高和粘合剂的韧性。用6 g NGDE粘合的胶合板的拉伸剪切强度比用6 g PAE粘合的胶合板拉伸剪切强度高19.1%，并且与MUF树脂相似，这验证了新型粘合剂适合用作工业胶合板粘合剂。