Propylene glycol
Description
Propylene glycol (CAS 57-55-6), commonly abbreviated as PG and approved as E1520 in food applications, is a synthetic diol used across food, pharmaceutical, personal care, and industrial sectors.
It functions primarily as a humectant, solvent, and carrier, retaining moisture in formulations and solubilizing active ingredients that are otherwise difficult to deliver effectively in various mediums.
In food and beverage manufacturing, PG carries flavors, colors, and preservatives in products where water or oil-based solvents are unsuitable for the specific formulation requirements of the manufacturer.
Pharmaceutical formulators rely on it as a solvent and co-solvent in oral liquids, topical creams, and injectable preparations where consistent solubility and stability are required for the final product.
Personal care producers use it to control moisture retention in lotions, serums, and hair care products while also improving texture and ingredient compatibility across a wide range of cosmetic applications.
In unsaturated polyester resin production, PG acts as a reactive diol in the polymer backbone, contributing to cross-linking and final resin performance for industrial and construction materials.
Propylene glycol is supplied as a clear, low-viscosity liquid in bulk, IBC, and drum formats. Recognized grades include USP/EP for pharmaceutical and food use, and FCC for food-grade applications.
Technical grade is available for industrial and polymer processing. USP and FCC grades are the most commonly specified by procurement teams sourcing for highly regulated global end markets.
Physical Properties
| Melting Point | -59 °C |
| Boiling Point | 188.2 °C |
| Density | 1.036 g/cm³ @ Temp: 25 °C |
| Flash Point | 225 °F |
| Appearance | Propylene glycol is a colorless, odorless, syrupy liquid. |
| Color | APHA: ≤10 |
| Odor | at 100.00 %. odorless very slight alcoholic |
| Form | Viscous Liquid |
| Water Solubility | miscible |
| Vapor Pressure | 0.08 mm Hg ( 20 °C) |
| Refractive Index | n 20/D 1.432(lit.) |
| pH | 6-8 (100g/l, H2O, 20℃) |
| Log P | -0.92 |
Safety & Handling (Learn More)
Trade & Regulatory
| HS Code | 29053200 |
| Storage Class | 10 - Combustible liquids |
| WGK (Germany) | 1 |
Documentation
Other Names
HOCH2CH(OH)CH3|DL-propylene glycol|DL-1,2-propanediol|CH3CH(OH)CH2OH|alpha-propyleneglycol|2,3-propanediol|2-hydroxypropanol|1,2-propylene glycol|PG|E1520
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