There is no simple answer “yes or no” to this question. If precisely, it is not an emulsifier although it can stabilize and thicken an emulsion.


However, it can be considered as an emulsifier if used together with sodium hydroxide (or in alkaline conditions) as it produces sodium stearate, which works as an emulsifier and helps oil and water phases mix well.

Benefits for skin
Stearic acid is often combined with emulsifiers to thicken and stabilize ointments, lotions, and emollients. It washes the oil, dirt, and other impurities that have accumulated on your skin away and retains moisture on the skin’s surface. Finally, it creates a cooling feel on the skin.  

Pharmaceuticals
Its derivative magnesium stearate, an excipient commonly used as a lubricant in pharmaceutical tablets & capsules and supplements.

Wax
Stearic acid can be used as a wax hardener in candle production. It can not only help pillars or freestanding candles maintain their shape in a warm temperature for a long time, but also increase the whiteness of wax and help demoulding. Plus, it stabilizes the perfume and aromas for a longer time.

Soap
Stearic acid hardens the soap bar, and creates a soft & creamy lather.

Rubber
This ingredient is used as a dispersing agent and accelerate the vulcanization process in rubber.

Plastics

In the plastics industry, stearate (lead, zinc, calcium, barium, magnesium, etc.) can be used as a heat stabilizer, which can interact with HCl degraded from polyvinyl chloride (PVC) to prevent PVC decomposition.

 

http://www.chinafooding.com/Stearic_Acid