Search results
Results from the WOW.Com Content Network
Polyurethane synthesis, wherein the urethane groups −NH−(C=O)−O− link the molecular units A kitchen sponge made of polyurethane foam . Polyurethane (/ ˌ p ɒ l i ˈ jʊər ə ˌ θ eɪ n,-j ʊəˈr ɛ θ eɪ n /; [1] often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links.
This colorless, flammable, and poisonous liquid, featuring a slight alcohol odor in its pure form, is miscible in water, ethanol, ketones, and various other organic solvents. Its principal applications include serving as an ingredient in antifreeze, dry gas, windshield washer fluids, and as a denaturant in ethanol. 13.
For example, in the United States flammable liquids, by definition, have a flash point below 100 °F (38 °C)—where combustible liquids have a flash point above 100 °F (38 °C). Flammable solids are solids that are readily combustible, or may cause or contribute to fire through friction.
Chemical foam is a stable solution of small bubbles containing carbon dioxide with lower density than oil or water, and exhibits persistence for covering flat surfaces. Because it is lighter than the burning liquid, it flows freely over the liquid surface and extinguishes the fire by a smothering (removal/prevention of oxygen) action.
As these chemicals are soluble in liquids-either water or dry cleaning fluid, these fabrics must be dry-cleaned with a non-liquid cleaning agent. [citation needed] The flame retardants work by coating the flammable fabrics with a mineral based barrier, preventing fire from reaching the fibres.
Due to the closed-cell nature of rigid polyurethane foams, PUR insulation has minimal water absorption, which coupled with an appropriate cover, makes it a particularly suitable in applications where bacterial growth is a concern. Polyurethane insulation is suitable for insulating pipes with surface temperatures ranging from -196°C to 148°C. [7]
Krytox is a fluorether-based vacuum grease, useful from −75 to over 350 °C, not flammable even in liquid oxygen, and highly resistant to ionizing radiation. Polyphenyl ether greases Torrlube , a brand encompassing a range of lubricating oils based on perfluoropolyethers .
Spray foam insulation extruding from a duct. Spray foam (expanding foam in the UK) is a chemical product created by a chemical reaction of two component parts, commonly referred to as side A and side B. [1] Side A contains very reactive chemicals known as isocyanate.