Effect of interfacial dilational rheology on the breakage of dispersed droplets in a dilute oil–water emulsion
Effect of interfacial dilational rheology on the breakage of dispersed droplets in a dilute oil–water emulsion
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DOI：
10.1016/j.colsurfa.2013.08.075
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
Wei Wang-;Kai Li;Pengyu Wang;Shuai Hao;J. Gong
中科院分区：
文献类型：
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作者：
Wei Wang-;Kai Li;Pengyu Wang;Shuai Hao;J. Gong
表面活性剂降低了油-水界面张力，从而有利于乳化，然而，很少有人关注界面扩张流变学对液滴破碎的影响。本工作的目的是流变学特性的油-水滴的界面特性和在乳化过程中的液滴破碎的影响。分散的含率在稀分散体中是固定的，其中在混合期间破碎占主导地位。采用聚焦光束反射法（FBRM）在线测量液滴总数、平方加权平均直径（sqr-wt）和弦长分布（CLD）。在分散液滴的变化进一步分析与界面扩张模量。对于表面活性剂浓度低于临界胶束浓度（CMC）的乳液，界面张力随着表面活性剂浓度的增加而减小，而平均液滴直径最初显示出增加的趋势，然后减小。然而，对于高于CMC的浓度，界面张力很少降低，而分散相的平均直径继续降低，并且液滴总数随着Span 80浓度的继续增加而增加。这表明界面扩张弹性是影响纯破碎乳化过程及其分散形态的关键因素。
Surfactants reduce the interfacial tension of oil–water and hence favor emulsification; however, attention has rarely been focused on the effect of interfacial dilational rheology on drop breakage. The aim of this work is to rheologically characterize the interfacial properties of oil–water droplets and the effect on drop breakage during emulsification. The dispersed holdups are fixed in dilute dispersion where breakage dominates during mixing. The total number of droplets, the square weighted (sqr-wt) mean diameter and the chord length distribution (CLD) are measured online using the focus beam reflectance method (FBRM). Variations in the dispersed droplets are further analyzed with the interfacial dilational modulus. For emulsions with surfactant concentrations below the critical micelle concentration (CMC), the interfacial tension decreases as the surfactant concentration increases, whereas the mean drop diameter initially shows an increasing trend and then decreases. However, for concentrations above the CMC, the interfacial tension rarely decreases, whereas the mean diameter of the dispersed phase continues to decrease, and the total number of droplets increases as the concentration of Span 80 continues to increase. This indicates that the interfacial dilational elasticity is a key factor that influences the pure breakage emulsification process and the related dispersed modality.