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101.
Polyfunctional aziridine/polyester microcapsules as control-release waterborne cross-linker were synthesized by multiple emulsion-solvent
evaporation method. The results show that, a lower surface free energy with shell polyester is more favourable for the formation
of microcapsules. Full encapsulating microcapsules are synthesized with the polyester with a surface free energy of 34.5 mJ/m2. Shell-to-core feeding mass ratio has a significant influence on the morphology and core content of the resulting microcapsules.
Well defined spherical microcapsules with uniform shell thickness and core content at around 22% are produced at a shell-to-core
mass ratio of 1:1. When 2.5% of colloid stabilizer is used, hollow spherical microcapsules are obtained. A high solvent evaporation
rate results in wrinkling and porosity of the microcapsules, and an evaporation rate equivalent to solvent elimination in
about 2 h provides a uniform rate of surface hardening. The characterization of the microcapsules by SEM and FTIR demonstrates
that polyfunctional aziridine is encapsulated at the centre of the microcapsule. The microcapsules synthesized can be broken
at a high shear rate. 相似文献
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Preparation and Characterization of Two-component Waterborne Poly-urethane Comprised of Water-soluble Acrylic Resin and HDI Biuret 总被引:12,自引:0,他引:12 下载免费PDF全文
ZHOUXinhua 《中国化学工程学报》2006,14(1):99-104
A two-component waterborne polyurethane (2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU particles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI isocyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction between HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density. 相似文献
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以HDI缩二脲为固化剂的双组分水性聚氨酯研究 总被引:4,自引:0,他引:4
以HDI缩二脲为固化剂,丙烯酸树脂为多元醇组分,得到稳定分散的双组分水性聚氨酯乳液,研究了溶剂、单体组成、相对分子质量、丙烯酸等因素。讨论了聚合温度和引发剂的选择,羟基丙烯酸树脂软硬单体、丙烯酸、n(—NCO)/n(—OH)对涂膜吸水率、二甲苯溶胀率等性能的影响。结果表明,聚合温度为140℃,引发剂占单体总质量的2%,m(DTAP)/m(DTBP)=7:3,羟基丙烯酸树脂单体转化率高、相对分子质量分布窄。羟基丙烯酸树脂单体组成为m(MMA):m(BA):m(AA):m(HEMA):38:34:6:22,n(—NCO)/n(—OH):1.6:l,涂膜吸水率小、交联密度高。 相似文献
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形状记忆聚氨酯是一种可以响应外界刺激,并通过特定的热力学过程回复到初始形态的新型智能高分子材料。基于不同的应用,提供形状展开功能、形状固定及回复功能、形状回复率及回复力可控等性能。形状记忆聚氨酯可以通过热、电、光、磁等方式直接或者间接地激发材料的形状记忆性能,在智能纺织、航空航天、生物医用等领域具有广阔的应用前景。首先介绍了形状记忆聚氨酯的结构、记忆机理和分类;然后讨论了影响其形状记忆性能的因素,主要包括硬段种类和含量的影响、软段的种类和相对分子质量的影响、交联剂的影响、掺杂填料的影响等。在此基础上总结了形状记忆聚氨酯在不同领域的应用进展,最后展望了形状记忆聚氨酯网络结构化设计思路和未来的发展方向。 相似文献
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嵌段离聚体包覆DCOIT纳米胶囊的合成、表征及其释放特性的研究 总被引:1,自引:0,他引:1
以PEG/IPDI/DMPA为原料,通过溶液聚合法,获得了嵌段离聚体溶液(溶剂为N,N-二甲基甲酰胺),然后在水相界面上对疏水功能性有机分子DCOIT进行自组装包覆制备DCOIT纳米胶囊。实验最终通过FT-IR、表面张力测试表征了嵌段离聚体的结构及性能,粒径分布和冷冻切片TEM和紫外-可见分光光度计对DCOIT纳米胶囊的形貌和释放特性进行了研究。研究结果表明,实验制备出了预期结构的聚氨酯嵌段离聚体,并形成了DCOIT纳米胶囊;DCOIT纳米胶囊的释放特性表现为,当壁芯比在1∶1至2∶1之间变化时,纳米胶囊都在释放初期速率较快,然后经历一个减速期,随后速率再次增加;且随着壁芯比的减小,DCOIT纳米胶囊的减速期越来越短。最后,对DCOIT纳米胶囊的释放机理进行了初步探讨。 相似文献
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介绍了羟基丙烯酸树脂的水分散规律及原理、溶液聚合的溶剂及水分散的助溶剂的选用方法。综述了制备高固体分低黏度羟基丙烯酸树脂水分散体的研究进展,主要包括提高聚合温度、选用过氧化二叔戊基等引发剂合成低分子量低交联度聚合物;合成核壳结构或以叔碳酸缩水甘油酯、叔碳酸乙烯酯、甲基丙烯酸苄酯、(甲基)丙烯酸异冰片酯、甲基丙烯酸环己酯、甲基丙烯酸叔丁基环己酯等功能单体合成枝化结构羟基丙烯酸树脂;采用多步聚合工艺制备具有特殊结构或较低分子量的共聚物,并对其原理进行了简要分析。最后总结了羟基丙烯酸树脂水分散体目前存在的一些问题,主要包括耐水耐溶剂性、稳定性、成膜性等;并对解决上述一系列问题的研究方向进行了展望,主要包括树脂结构、成膜机理、涂料配方等。 相似文献
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