流变调节剂对W/O型乳液稳定性和流变性的影响

Effects of rheological modifiers on the rheological properties and stability of W/O emulsions

采用均质乳化法制备了W/O型乳液,研究了高分子水溶性聚合物(黄原胶、透明质酸钠)和油相增稠剂(山嵛酸甘油酯、二甲基二硬脂基铵锂蒙脱石)对W/O型乳液稳定性和流变性的影响。实验结果表明,添加黄原胶后,W/O型乳液在不同稳定性测试条件下的稳定性均下降;添加透明质酸钠后,乳液的常温储存稳定性下降,但一定程度上提升了乳液的高温储存稳定性;山嵛酸甘油酯加入W/O型乳液体系后,常温和高温储存的稳定性均增加;二甲基二硬脂基铵锂蒙脱石添加后,乳液在不同条件下稳定性均增强。高分子水溶性聚合物加入后,内水相黏度上升,但W/O型乳液的表观黏度显著降低且线性黏弹区范围缩小,这可能是由于内水相黏度升高阻碍乳化剂分子在油/水界面的吸附;油相增稠剂的添加均增加了W/O型乳液的表观黏度和线性黏弹区范围,这可能和乳化粒子粒径降低和油/水界面能的变化有关。此外,流变调节剂加入后,乳液的滞后环面积均有不同程度的降低。

W/O emulsions were prepared by homogeneous emulsification method. The effects of water-soluble polymers(xanthan gum and sodium hyaluronate) and oil-phase thickeners( glyceryl behenate and dimethyl distearyl ammonium lithium-montmorillonite) on the stability and rheological properties of W/O emulsions were studied. The experimental results showed that the stability of W/O emulsions was decreased under different stability testing conditions after the addition of xanthan gum. When sodium hyaluronate was added, the storage stability of the emulsion was decreased at room temperature, but the storage stability at high temperature was improved. The storage stabilities at room temperature and high temperature were both increased when glyceryl behenate was added to the W/O emulsions. With the addition of dimethyl distearyl ammonium lithium-montmorillonite, the stability of the emulsion was enhanced under different conditions. After the addition of water-soluble polymers, the water-phase viscosity was increased, but the apparent viscosity of W/O emulsions was significantly decreased and the range of linear viscoelastic region became narrow. This might be due to the increased viscosity of the inner water phase which prevented the adsorption of emulsifier molecules at the oil/water interface. The apparent viscosity and linear viscoelastic region of W/O emulsions were both increased with the addition of oil-phase thickeners, which might be related to the decrease of emulsion droplet size and the change of oil-water interface energy. In addition, the hysteresis loop area of emulsions was decreased to different extent with the addition of rheological modifiers.