基于耗散粒子动力学的淀粉基胶黏剂失稳机制研究

Starch-based adhesives will be a main household wood adhesive for its renewable raw materials and free of formaldehyde. However, the industrial application of starch-based wood adhesives is limited by their poor stability and easily aggregation. In order to solve this issue, the aggregation process of starch-based wood adhesive colloids will be investigated in this study. The in situ aggregation behavior will be revealed by using Small angle x-ray scattering analyzer, dynamic light scattering, atomic force microscope and other modern instruments. The aggregation mechanism would further studied through the aggregation behavior between starch-based wood adhesive colloids. In addition, the aggregation model of starch-based wood adhesive colloids will be simulated by the dissipative particle dynamics algorithm. Based on the basis of aggregation model, the effect of environment impact factors on the aggregation behavior of starch-based wood adhesive colloids was further studied. The regulation of storage stability of starch-based adhesive could be provided by the aggregation theory. Multi-objective optimization technology will also be used to optimize the synthetic process of starch-based adhesives and improve the bonding performance and stability of starch-based wood adhesive. Furthermore, this study will provide a beneficial strategy for the regulation of aggregation behavior and stability of other complex fluid systems.

淀粉基木材胶黏剂由于原料可再生、不含甲醛，而被视为新一代环保型家装用胶黏剂的典型代表。但淀粉胶稳定性差，极易发生团聚，严重制约了其工业化进程。本研究针对淀粉胶制备的薄弱环节，以胶黏剂颗粒的团聚行为为研究对象，旨在通过对胶黏剂颗粒团聚过程的解析，为淀粉胶团聚行为的可控调节提供理论依据。采用小角X射线散射、动态光散射、原子力显微镜等仪器表征手段原位监测颗粒的团聚过程，关联不同阶段颗粒间的作用方式，从介观尺度揭示淀粉胶颗粒的团聚机制；进而结合耗散粒子动力学模拟等计算方法，构建颗粒的团聚模型；以该模型为参照，判别不同环境条件对淀粉胶颗粒团聚行为的影响，揭示环境因素对淀粉胶团聚的作用方式及本质规律。在此基础上，通过多目标模拟优化等技术手段，对淀粉胶制备工艺参数进行优化，以提高淀粉胶的稳定性。此外，本项目的相关技术手段及视角将为研究其他复杂流体体系中颗粒团聚行为，提高其贮藏稳定性提供技术借鉴。

淀粉基木材胶黏剂由于原料可再生、不含甲醛，而被视为新一代环保型家装用胶黏剂的典型代表。但淀粉胶稳定性差，极易发生团聚，严重制约了其工业化进程。本研究以淀粉胶黏剂颗粒的团聚行为为研究对象，采用耗散粒子动力学模拟计算，构建淀粉胶的团聚模型，从介观尺度解析了典型乳化剂抑制淀粉胶颗粒团聚行为的相关机制。主要研究结果如下：.1、针对淀粉胶容易发生团聚的现象，利用低场核磁、多重光散射等技术研究了典型淀粉团聚体系——酸解处理时间对淀粉胶团聚行为影响。结果表明不同酸解时间对团聚现象的影响程度不同，淀粉胶的团聚行为主要由淀粉分子的老化行为驱动；适度的酸水解处理有助于提高单体接枝效率，提高淀粉胶黏剂的粘度稳定性，粘合能力和防水性能。 .2、 系统研究了乳化剂抑制淀粉胶颗粒团聚行为的相关机制。根据表观结果确定十二烷基硫酸钠（SDS）抑制淀粉胶颗粒团聚效果最佳；搭建了基于耗散粒子动力学的计算机模拟平台，结合表观分析及构建淀粉胶的团聚模型证实SDS可通过限制淀粉链的旋转，降低体系界面张力，促进淀粉与单体分子发生接枝反应。此外，SDS还可促进淀粉胶粒子分散，从而抑制淀粉胶颗粒的团聚。.3、添加纳米二氧化钛提高淀粉胶的粘结性能。利用小角X射线（SAXS），DMA等测试手段证实纳米TiO2提高淀粉胶粘结性能的相关机制为：纳米TiO2能均匀的分散在淀粉胶形成的胶膜中，通过氢键等作用力和淀粉接枝共聚物作用，形成了较好的网络结构，提高了淀粉胶膜的粘弹性和抗粘性变形性能，进一步提高淀粉胶的粘结性能。.4、通过引入丙烯酸正丁酯作为第二单体提高淀粉胶的综合性能。结果表明，醋酸乙烯酯：丙烯酸正丁酯比例为6:4的时候，淀粉胶综合性能最好，室温下储藏稳定性可达1年，相关机制在于丙烯酸正丁酯通过降低淀粉胶的玻璃化转变温度，促进连续柔性膜的形成。同时还可抑制胶乳颗粒的聚集，为淀粉胶的工业化应用奠定了相关的研究基础。