Skim through

What it does: solvent, moisturizer/humectant, emollient

Also called: zemea 

The science

Propanediol is a natural alternative for propylene glycol. It's produced sustainably from corn sugar. It can be used to improve moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula.

Benefits for your hair

Promotes hydration

Propanediol helps to improve moisturization in the scalp and hair, which further helps to reduce frizz and soften the hair.

Improves texture 

Propanediol helps improve the texture and feel of the product during application, making it a much smoother and efficient process. 

TLDR 

Propanediol is a good emollient, helping to soften and moisturize the hair while improving product texture.