PPG-6, PPG-8, PPG-12, PPG-40, PPG-150, etc.
Polypropylene glycol is a family of long chain polymers attached to a glycerine backbone.
Like the closely related compound polyethylene glycol, PPG is used as a thickener in many products. It is used in toothpaste to prevent bacteria from breaking down the pyrophosphates used to control tartar buildup.
propylene glycol: InChI=1/C3H8O2/c1-3(5)2-4/h3-5H,2H2,1H3