Propylene Glycol and Its Various Useful Properties

Propylene glycol is a more environmentally friendly option than ethylene glycol and should be used where the possibility of contamination of waterways, vegetation or soil can occur. It can be formulated as an effective solvent or as an ingredient in deodorants, cosmetics, food, and pharmaceuticals, to maintain moisture in the products. The Material Safety Data Sheet describes propylene glycol as a colourless liquid that is more viscous than water, and with a slightly sweet flavour. Its boiling point is 188^oC, and the melting point is -22^oC, with a specific gravity of 1.036, making it slightly denser than water. It cannot evaporate to a significant degree, so its vapour pressure remains negligible at normal room temperature.

Propylene glycol is stable, and doesn’t decompose over time. It has low toxicity, low vapour pressure, and a low freeze point, however, it is  flammable at high temperatures. When mixed with water, propylene glycol interrupts ice formation, making it an effective antifreeze or de-icer. Water may freeze at 0^oC, but adding propylene glycol in a 36 percent concentration ensures the water will remain liquid to -18^oC, and more concentrated solutions will remain liquid at lower temperatures.

Propylene glycol is also used in HVAC systems and must contain corrosion inhibitors to counteract acids formed by oxidation of the glycol. Rust or corrosion of metal will decrease the life of the pipes, boilers and other equipment, making inhibitors necessary.

Industrial grade propylene glycol may be recommended where ethylene glycol is unsafe or not recommended, and where you may need to be environmentally sensitive. Many industries use it for different applications, like de-icing, anti-freeze, and hydro-testing, so it is often sold in different grades and blends. Reputable chemical distributors and suppliers can deliver propylene glycol in different methods and in any preferred storage medium, like in bulk, tote, drums, or pails to suit your application.