ABSTRACT

In this paper, we first report the preparation of poly (urea–formaldehyde) (UF) microcapsules filled with liquid polysulfide by one-step in situ polymerization. For obtaining the optimal preparation condition, the influences of various process factors including emulsifier type and its usage, initial pH value of the solution, reaction temperature and time on the dispersion, and encapsulation effects of liquid polysulfide were experimentally investigated. The structure and morphology of the prepared microcapsules were characterized by Fourier-transform infrared spectroscopy, optical microscopy, and scanning electron microscopy, respectively. The relative content of liquid polysulfide in microcapsules was determined using ultraviolet spectrum method. Furthermore, the mechanical properties of cured liquid polysulfide films before and after encapsulation were measured according to the relative standards. Results indicated that the liquid polysulfide was successfully encapsulated in UF microcapsules, which had a well-defined spherical shape, a continuous inner shell wall, a rough exterior surface, and an average diameter of about 200 μm. The breakaway, disassembly torques, tensile strength, and hardness of microcapsule sealant were greatly improved in comparison with those of unencapsulated one. The study provides a valuable support for the automatic pre-coating technology of polysulfide sealants in the future.

摘要

在本文中，我们首先报道了一步原位制备填充液态多硫化物的聚（脲-甲醛）（UF）微胶囊。聚合。为获得最佳制备条件，实验研究了乳化剂类型及其用量、溶液初始pH值、反应温度和反应时间等多种工艺因素对液体多硫化物分散和包封效果的影响。分别通过傅里叶变换红外光谱、光学显微镜和扫描电子显微镜对制备的微胶囊的结构和形貌进行了表征。采用紫外光谱法测定微胶囊中液态多硫化物的相对含量。此外，根据相关标准测量了封装前后固化的液态聚硫化物薄膜的机械性能。结果表明，液态多硫化物被成功包封在超滤微胶囊中，该微胶囊具有明确的球形、连续的内壳壁、粗糙的外表面和约200 μm的平均直径。与未封装的相比，微胶囊密封胶的分离、拆卸扭矩、拉伸强度和硬度都有很大的提高。该研究为未来聚硫密封胶的自动预涂技术提供了宝贵的支持。