大豆蛋白胶黏剂强弱双交联网络构建及其增强增韧机制研究

The water resistance of soy protein adhesive can be effectively improved by the cross-linking modification, however, the modified adhesives have poor wettability to wood and the cured adhesive layers have high brittleness, resulting in poor stability of bonding strength of bonded products, which restricts the development and application. According to the theory of enhancing and toughening materials by cross-linking double network, the investigation intends to construct the strong/weak cross-linking double network structure in the soy protein adhesive system based on the molecular structure design and regulation, to achieve the toughening and enhancing of the adhesive, and to improve the interface force between the adhesive and wood. The first covalent bond cross-linking network is constructed by using soy protein and epoxide or other cross-linking agents, and the second cross-linking network is from weak cross-linking system formed by the hydrogen bond and coordination bond, which is constructed by catechol, metal ion, amino group, etc.. The construction conditions for the double network of different types and properties are studied, meanwhile the influences of double network on the adhesive properties and the wettability and permeability to the wood surface are analyzed, furthermore, the influential mechanisms of the double network on the interface between the adhesive and wood are revealed. The effects of double network on the curing and bonding properties of soy protein adhesives are studied, and the influence rules of the stress in soy protein adhesive double network during the bonding failure process are revealed, in the meantime, the enhancing and toughening mechanisms are explained. The new ideas and methods for modification and property improvement of protein-based wood adhesives will be provided by the investigation, which will help to promote the industrial application of protein-based adhesives.

交联改性可有效提高大豆蛋白胶黏剂耐水胶接性能，但改性胶黏剂对木材润湿性差、固化胶层脆性大，导致胶接产品胶合强度稳定性差，制约其推广应用。本项目拟以材料双交联网络增强增韧理论为指导，从分子结构设计与调控入手，在大豆蛋白胶黏剂体系中构建强弱双交联网络结构，实现胶黏剂增韧增强，提高胶黏剂与木材界面作用力。采用环氧化合物等交联剂与大豆蛋白构建第一共价键交联网络，引入邻苯二酚、金属离子、氨基等功能基团构建氢键/络合键等弱交联形成第二网络，研究不同类型和特性的双网络结构构建条件，解析双网络结构对胶黏剂性能及对木材表面润湿性、渗透性等的影响，解明双网络对胶黏剂与木材界面作用影响机制；研究双网络对大豆蛋白胶黏剂固化及胶接特性影响，揭示双网络对大豆蛋白胶黏剂胶接破坏过程应力作用影响规律，解明其增强增韧机制。项目将为蛋白基木材胶黏剂改性和性能提高提供新思路与新方法，有助于推动蛋白基胶黏剂的规模化工业应用。

大豆蛋白胶黏剂由于胶接性能差、黏度高、工艺性差等缺点制约其大规模推广应用。交联改性可有效提高大豆蛋白胶黏剂耐水胶接性能，但改性胶黏剂存在对木材润湿性差、固化胶层脆性大、胶接产品胶合强度稳定性差等问题。本项目以材料双交联网络增强增韧理论为指导，从分子结构设计与调控入手，在大豆蛋白胶黏剂体系中构建强弱双交联网络结构，实现胶黏剂增韧增强，提高胶黏剂与木材界面作用力。采用环氧化合物等交联剂与大豆蛋白构建第一共价键交联网络，引入邻苯二酚、金属离子、氨基等功能基团构建氢键/络合键等弱交联形成第二网络，制备胶黏剂耐水性提高，胶黏剂制备的胶合板的干、湿剪切强度分别显著提高，胶膜断裂伸长率和断裂韧性显著增强，同时固化胶黏剂断面裂纹消失，表明胶黏剂韧性提高。胶黏剂黏度降低，提高了胶黏剂渗透性，与木材形成更多机械结合，共价键网络消耗了活性基团，提高了胶黏剂的耐水性，动态键网络耗散能量，提高了胶黏剂韧性，单宁酸中酚类物质与金属离子协同作用，使合成胶黏剂具有优异的防霉性能。研究揭示双网络对大豆蛋白胶黏剂胶接破坏过程应力作用影响规律，解明其增强增韧机制。为蛋白基木材胶黏剂改性和性能提高提供新思路与新方法，有助于推动蛋白基胶黏剂的规模化工业应用。项目研究成果发表论文19 篇，其中第一标注SCI 收录论文9篇，中文核心论文2篇，第二标注SCI 收录论文8篇；获授权发明专利3项，申请发明专利3项；培养研究生3人，参加国际会议2次。