In situ poly(urea-formaldehyde) microencapsulation of dicyclopentadiene
In situ poly(urea-formaldehyde) microencapsulation of dicyclopentadiene
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DOI：
10.1080/0265204031000154160
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发表时间：
2003-11-01
影响因子：
3.9
通讯作者：
White, SR
中科院分区：
文献类型：
--
作者：
Brown, EN;Kessler, MR;White, SR
微胶囊修复材料需要具有足够的强度、较长的保质期和与宿主材料良好的粘附性。采用水包油乳液原位聚合法制备了含双环戊二烯的脲醛微胶囊，满足了环氧树脂自愈的要求。通过在200-2000rpm范围内适当选择搅拌速度，可制备出直径为10-1000微米的微胶囊。对数(平均直径)和搅拌速率(对数)之间存在线性关系。用光学显微镜和电子显微镜观察了壳体的表面形貌和壳壁厚度。微胶囊由160-220 nm光滑的内膜和粗糙、多孔的聚结的尿素-甲醛纳米颗粒组成。表面形态受反应乳状液的pH值和核水界面的界面表面积的影响。CHN分析表明，球状微胶囊的填充量为83-92wt%，可获得高得率(80-90%)的球形微胶囊。
Microencapsulated healing agents that possess adequate strength, long shelf-life and excellent bonding to the host material are required for self-healing materials. Urea-formaldehyde microcapsules containing dicyclopentadiene were prepared by in situ polymerization in an oil-in-water emulsion that meet these requirements for self-healing epoxy. Microcapsules of 10-1000 mum in diameter were produced by appropriate selection of agitation rate in the range of 200-2000 rpm. A linear relation exists between log(mean diameter) and log(agitation rate). Surface morphology and shell wall thickness were investigated by optical and electron microscopy. Microcapsules are composed of a smooth 160-220 nm inner membrane and a rough, porous outer surface of agglomerated urea-formaldehyde nanoparticles. Surface morphology is influenced by pH of the reacting emulsion and interfacial surface area at the core-water interface. High yields (80-90%) of a free flowing powder of spherical microcapsules were produced with a fill content of 83-92 wt% as determined by CHN analysis.