Abstract The introduction of epoxy crosslinking agents is an efficient path to improve the water resistance and adhesion properties of a soy protein-based adhesive. However, it is still a challenge to directly incorporate cheap epoxy resin into a protein system other than by an expensive epoxy diluent. In this work, a waterborne epoxy emulsion (WEU) was prepared by grafting hydrophilic groups onto bisphenol-A (E44) followed by a phase-transformation process for the oil-in-water emulsion, with the aim to modify a soy protein-based adhesive. The effects of different neutralizers on the performance of the resulting adhesive were also analyzed. The prepared WEU presented excellent stability and admirable dispersibility in the adhesive system, as confirmed by digital photos, and served as an active crosslinker, contributing to multiple stable crosslinking networks with soy protein molecules, as characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal gravimetric analysis. The results showed that a soy protein-based adhesive crosslinked by WEU neutralized by triethylamine could endow plywood with 20% higher wet shear strength than that of being crosslinked by WEU neutralized by N, N-dimethyl ethanolamine, which reached 1.14 MPa and 192.5% increment compared to a neat soy protein-based adhesive. Moreover, the residual rate of modified soy protein adhesives increased 4.2% while the moisture uptake of modified soy protein adhesives decreased 8.5% compared to pure SP adhesive. The authors hypothesize that the epoxy crosslinking modification of soy protein with WEU may be an effective method to fabricate high-performance soy protein-based adhesives for practical applications.

中文翻译：

---

水性环氧交联策略开发具有高耐水性和粘接强度的大豆蛋白基胶粘剂

摘要 环氧交联剂的引入是提高大豆蛋白基胶粘剂耐水性和粘合性能的有效途径。然而，除了通过昂贵的环氧树脂稀释剂之外，将廉价的环氧树脂直接掺入蛋白质系统仍然是一个挑战。在这项工作中，通过将亲水基团接枝到双酚 A (E44) 上，然后对水包油乳液进行相转变过程，制备了水性环氧乳液 (WEU)，目的是对基于大豆蛋白的乳液进行改性。粘合剂。还分析了不同中和剂对所得粘合剂性能的影响。数码照片证实，制备的 WEU 在粘合剂体系中表现出优异的稳定性和令人钦佩的分散性，并作为活性交联剂，与大豆蛋白分子形成多重稳定的交联网络，如傅里叶变换红外光谱、扫描电子显微镜和热重分析所表征。结果表明，与N,N-二甲基乙醇胺中和WEU交联的胶合板相比，三乙胺中和WEU交联大豆蛋白基胶粘剂，胶合板湿剪切强度提高20%，达到1.14 MPa，增加192.5%与纯大豆蛋白基粘合剂相比。此外，与纯SP粘合剂相比，改性大豆蛋白粘合剂的残留率增加了4.2%，而改性大豆蛋白粘合剂的吸湿率下降了8.5%。