Shrestha Lok Kumar, Shrestha Rekha Goswami, Sharma Suraj Chandra, Aramaki Kenji
Graduate School of Environment and Information Sciences, Yokohama National University, Tokiwadai 79-7, Hodogaya-ku, Yokohama, Japan.
J Colloid Interface Sci. 2008 Dec 1;328(1):172-9. doi: 10.1016/j.jcis.2008.08.051. Epub 2008 Sep 3.
Nonaqueous foams stabilized by lamellar liquid crystal (L alpha) dispersion in diglycerol monolaurate (designated as C12G2)/olive oil systems are presented. Foamability and foam stability depending on composition and the effects of added water on the nonaqueous foaming behavior were systematically studied. It was found that the foamability increases with increasing C12G2 concentration from 1 to 3 wt% and then decreases with further increasing concentration, but the foam stability increases continuously with concentration. Depending on compositions, foams are stable for a few minutes to several hours. Foams produced by 10 wt% C12G2/olive oil system are stable for more than 6 h. In the study of effects of added water on the foaming properties of 5 wt% C12G2/olive oil system, it was found that the foamability and foam stability of 5 wt% C12G2/olive oil decreases upon addition of 1 wt% water, but with further increasing water, both the foamability and foam stability increase. Foams with 10% water added system are stable for approximately 4 h. Phase behavior study of the C12G2 in olive oil has shown the dispersion of L alpha particles in the dilute regions at 25 degrees C. Thus, stable foams in the C12G2/olive oil system can be attributed to L alpha particle, which adsorb at the gas-liquid interface as confirmed by surface tension measurements and optical microscopy. Laser diffraction particle size analyzer has shown that the average particle diameter decreases with increasing the C12G2 concentration and, hence, the foams are more stable at higher surfactant concentration. Judging from foaming test, optical micrographs, and particle size, it can be concluded that stable nonaqueous foams in the studied systems are mainly caused by the dispersion of L alpha particles and depending on the particle size the foam stability largely differs.
本文介绍了由层状液晶（Lα）分散在甘油单月桂酸酯（记为C12G2）/橄榄油体系中稳定的非水泡沫。系统研究了取决于组成的发泡性和泡沫稳定性以及添加水对非水发泡行为的影响。结果发现，发泡性随着C12G2浓度从1 wt%增加到3 wt%而增加，然后随着浓度进一步增加而降低，但泡沫稳定性随着浓度持续增加。根据组成不同，泡沫可稳定几分钟到几小时。由10 wt% C12G2/橄榄油体系产生的泡沫稳定超过6小时。在研究添加水对5 wt% C12G2/橄榄油体系发泡性能的影响时发现，添加1 wt%水后5 wt% C12G2/橄榄油的发泡性和泡沫稳定性降低，但随着水进一步增加，发泡性和泡沫稳定性均增加。添加10%水的体系的泡沫稳定约4小时。对C12G2在橄榄油中的相行为研究表明，在25℃时Lα颗粒在稀区分散。因此，C12G2/橄榄油体系中的稳定泡沫可归因于Lα颗粒，表面张力测量和光学显微镜证实其吸附在气液界面。激光衍射粒度分析仪表明，平均粒径随着C12G2浓度增加而减小，因此，在较高表面活性剂浓度下泡沫更稳定。从发泡试验、光学显微照片和粒径判断，可以得出结论，所研究体系中稳定的非水泡沫主要由Lα颗粒的分散引起，并且根据粒径不同泡沫稳定性有很大差异。
