home > Paints & Coatings > Propylene Glycol (USP)

Propylene Glycol (USP)

CAS # 57-55-6


Propylene Glycol USP/EP is used as an excipient (non-active ingredient) in the manufacture of pharmaceutical products. It is also used as a humectant and emulsifier in the production of food and personal care products and in liquid laundry detergents.


AppearanceColorless Liquid
Freezing Point-60°C (-76°F)
Boiling Point @ 760mm Hg187°C (369°F)
Density @ 25°C1.032 kg/L 8.62 lb/gal
Vapor Pressure @ 25°C<0.1 mmHg
Vapor Density (air = 1)2.52
Solubility in Water @ 20°C100%
Refractive Index @ 20°C1.4329
Viscosity @ 20°C56.0 cP
Dielectric Constant @ 20°C (esu)32.0
Heat of Vaporization @ 25°C711 joules/g
Specific Heat @ 25°C2.481 J/(g°C)



·        Solvent and provide equal distribution of the active ingredient in the formulation, so that each pill, liquid dose or cream-based application always contains the exactly prescribed amount of curing agent.

·        Emollient for softening and smoothing is complex mixtures of chemical agents specially designed to make the external layers of the skin softer and more pliable, by increasing its hydration (water content) by reducing evaporation.

·        Humectants are used in topical dosage forms to increase the solubility of the active ingredient, to elevate its skin penetration and increase its activity time. Humectants also elevate the hydration of the skin to minimize the dehydrating effect of some active ingredients.

·        PG USP is also used additives, such as emulsion stabilizer, dispersant, coupling agent, viscosity modifier in pharmaceutical application.

·        Plasticizer in aqueous film coating formulation.