共查询到17条相似文献,搜索用时 296 毫秒
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不完全相反转发展过程的流变行为 总被引:6,自引:0,他引:6
以动态应力流变仪DSR(DynamicStresRheometer)对双酚A型环氧树脂在低乳化剂浓度(233wt%)下的相反转乳化过程进行了稳态应力扫描及动态频率扫描实验.实验结果表明,体系在相反转点前表现为牛顿流体行为,粘度几乎不变;相反转点时,体系粘度增加幅度很小,体系的有关动态流变参数(剪切储能模量、损耗模量和复数粘度)均出现极小值,将此归于局部连续水相的润滑作用;进一步加水,体系的动态流变量增加,意味着相反转在相反转点后仍在继续进行.所以,体系在低乳化剂浓度时,发生了不完全相反转. 相似文献
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环氧树脂相反转乳化过程相态发展研究 总被引:30,自引:1,他引:29
以扫描电镜为主要手段,观察了环氧树脂相反转乳化过程中的相态演化过程.结果表明:在较高乳化剂浓度下,当水含量达到某一临界值时,原W/O体系中水滴间的相互吸引大于水滴间的排斥作用,导致相邻水滴同时快速地融合为连续相并得到水基微粒,水基微粒的尺寸较小,约为亚微米级,尺寸分布窄,微粒为单个粒子.在乳化剂浓度较低情况下,非相邻较大水滴在剪切场作用下随机地融合为连续相,发生不完全相反转,并得到W/O/W结构,水基微粒尺寸较大,约10微米数量级,尺寸分布宽且为一种复合多孔结构.此外,分析了相反转发展演变过程. 相似文献
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乳化剂分子亲水组分含量对相反转乳化过程的影响 总被引:16,自引:0,他引:16
高分子树脂水基分散体系 ,因其结构的可灵活调节性 ,在许多方面得到应用 ,又因其不含有机溶剂 ,能完全满足环境保护和生态的要求而备受关注 [1~ 3] .相反转乳化技术是制备高分子水基体系的新方法 ,它适用于制备包括加聚物和缩聚物的大多数高分子水基体系 ,大大拓宽了水基体系的范围 [4 ] .杨振忠等[5] 利用自己合成的高分子非离子型乳化剂将环氧树脂乳化成微粒尺寸小且分布窄的水基分散体系 ,对相反转机理和相反转技术进行了深入研究 .研究表明 ,乳化剂浓度和乳化温度对相反转后水基微粒尺寸和形态有重要影响 ,高乳化剂浓度和较低的乳化温… 相似文献
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不完全相反转乳化过程分散相水滴形态发展研究 总被引:3,自引:0,他引:3
相反转乳化技术是制备高分子树脂水基分散体系的新方法[1~4].相反转指多组分体系(如油/水/乳化剂)中的连续相在一定条件下相互转化的过程,如在油/水/乳化剂体系中,其连续相由水相向油相(或从油相变为水相)的转变.在连续相转变区,体系的界面张力最低,因而分散相的尺寸最小.同理,可利用相反转技术直接将高分子树脂乳化为尺寸很小的水基微粒,即制备高分子树脂的水基分散体系.由于高分子树脂的粘弹性及相反转过程的复杂性,对高分子树脂的相反转乳化过程的机理研究较少.杨振忠[5]等通过调节高分子非离子型乳化剂浓度,可以有效地控制相反转完善程… 相似文献
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以扫描电镜为主要手段,观察了环氧树脂相反转乳化过程中的相态演化过程.结果表明
在较高乳化剂浓度下, 当水含量达到某一临界值时, 原W/O体系中水滴间的相互吸引大于水滴间的排斥作用,
导致相邻水滴同时快速地融合为连续相并得到水基微粒,
水基微粒的尺寸较小, 约为亚微米级, 尺寸分布窄,微粒为单个粒子.在乳化剂浓度较低情况下,非相邻较大水滴在剪切场作用下随机地融合为连续相,发生不完全相反转,
并得到W/O/W 结构, 水基微粒尺寸较大,约10微米数量级,尺寸分布宽且为一种复合多孔结构.此外,分析了相反转发展演变过程. 相似文献
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CPDB/正丁醇/正辛烷/水体系溶致液晶的^2HNMR和DSC法研究 总被引:10,自引:1,他引:10
测定了溴化十六烷基吡啶/正丁醇/正辛烷/水体系的相平衡,在液晶区域选取样品点,用^2HNMR和差示扫描量热法,并与液晶纹理相对照研究了该区域的相结构变化,结果表明,在一定温度下,随着含水量的增加,体系从单一的W/O型微乳液→微乳液和层状液晶共存→层状液晶与六角状液晶共存→层状、六角状与六角状向立方状过渡晶型的三相共存→立方状→O/W型微乳液过度,在组成固定情况下,研究了该体系液晶相结构随温度升高所 相似文献
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相反转乳化技术制备环氧树脂交联多孔微球 总被引:2,自引:0,他引:2
多孔微球在分离吸附、催化、涂料印刷等多方面具有潜在应用价值 .最近研究表明 ,当微孔孔径在 2 0 0~ 80 0nm范围时 ,由于强烈的光散射作用 ,多孔微球可以作为遮光剂使用[1] .Okubo等用酸碱逐步处理法制备了一些共聚物的亚微米级多孔球[2~ 4] .Okubo又用动态溶胀种子聚合法制备了微米级的聚合物微球 ,用类似的方法得到了多孔结构[5,6] .但这种方法涉及了许多烦琐过程并且产生了很多副产物需要处理 ,使得其费时费力而且成本相当高 .Schlarb等发展了一种新的制备方法 ,在乳液聚合过程中引入有机溶剂 ,在实验后期除掉有机… 相似文献
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Zhen-zhong Yang De-lu Zhao Polymer Physics Laboratory Institute of Chemistry Chinese Academy of Sciences Beijing China 《高分子科学》2000,(1):33-38
The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions byPIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution duringphase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsificationtemperature on phase inversion progress and the structural features of the waterborne particles were studied as well. Thedeformation and break up of water drops in a shear field were analyzed in terms of micro-rheology, while the interaction andcoalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory,respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress wassuggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborneparticles were interpreted and predicted. 相似文献
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PREPARATION OF WATERBORNE ULTRAFINE PARTICLES OF EPOXY RESIN BY PHASE INVERSION TECHNIQUE 总被引:4,自引:0,他引:4
Werborne ultrafine particles of epoxy resin were prepared by phase inversion tech-nique. The results of SEM revealed that the particles diameter was in the range of 50to 100 nm and the effects on amount of water required at phase inversion point were alsodisc?d. 相似文献
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Waterborne dispersions of bisphenol A epoxy resin were prepared by the so-called phase-inversion emulsification technique.
The electrical properties, rheological behavior and morphological evolution during the phase inversion process were characterized
systematically. It was shown that both emulsifier concentration and emulsification temperature play great roles in controlling
the phase inversion process as well as the structural features of the waterborne particles. A high emulsifier concentration,
i.e. 10.90 wt% and a low emulsification temperature, i.e. 73 °C, facilitate complete phase inversion, in which all water droplets
in the system are simultaneously transformed into the continuous phase at the phase-inversion point (PIP). In this case, sub-micron-sized,
discrete waterborne particles were formed. In contrast, a complex water-in-oil-in-water structure was achieved by incomplete
phase inversion at a low emulsifier concentration, i.e. 2.33 wt%, and a high temperature of 80 °C. The morphological evolution
observed by scanning electron microscopy revealed that not all the water droplets in the system were converted into the continuous
phase at the PIP and that some small water drops were trapped within the waterborne structure.
Received: 15 March 2000/Accepted: 16 May 2000 相似文献
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两亲性梳状聚醚硅氧烷对相转化法聚偏氟乙烯多孔膜的共混改性作用研究 总被引:1,自引:0,他引:1
以聚醚链段为侧链的两亲性梳状聚醚硅氧烷(ACPS)为改性剂,研究了相转化法制备聚偏氟乙烯(PVDF)多孔膜的改性效果与机理.采用SEM、XPS、接触角、水通量等考察了ACPS对膜结构与性能的影响.研究发现,ACPS在相转化成膜过程中不流失,随着制膜液中ACPS含量的增加,相分离速度降低,膜中微孔由指状结构向蜂窝状结构发展,膜强度提高,亲水性显著提高.提出了ACPS在膜表面的富集现象和在膜中的稳定性机理和模型.结果表明,两亲性梳状聚醚硅氧烷在原理上是一类适合于相转化法制备聚合物微孔膜表面亲水化改性的有效物质. 相似文献