Polar emollients increase the stability of o/w emulsions, while moderately polar emollients have the best stability in re-w/o emulsions. They can also be moderately sized by combining different emollients. Sex. The polarity is judged by measuring the surface tension, and the greater the surface tension, the higher the polarity.
The emollient of polar emollients is superior to non-polar emollients having similar viscosities, and among polar emollients, the skin emollients of linear esters are more refreshing than glycerides. Generally speaking, as the molecular weight increases, the viscosity increases, and the skin feel of the emollient becomes thicker and thicker; the softness and smoothness of the unsaturated fatty acid esters are better than the corresponding saturated fatty acid esters.
In the w/o emulsion, the molecular weight of the oil is important, which directly affects the viscosity and stability of the emulsion. The higher the molecular weight, the higher the viscosity of the emulsion and the better the stability of the system. The emollients can be divided into three categories according to the spreading factor: one is > 1000 mm 2 / 10 minutes for high spreadability, with a light and smooth skin feel; the other is 500 to 1000 mm 2 / 10 minutes for medium spreadability; One type is <500mm2/10 minutes for low spreadability.