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urea Chem.|juːˈriːə, ˈjʊərɪə|
[ad. (with Latinized ending) F. urée (1803), f. Gr. οὖρον urine, or the verb οὐρέω. Cf. It., Sp., Pg. urea.]
1. a. A soluble crystalline compound, forming an organic constituent of the urine in mammalia, birds, and some reptiles, and also found in the blood, milk, etc.; carbamide, CO(NH2)2.
1806Phil. Trans. XCVI. 374 A decomposition of a portion of urea. 1819Brande Chem. 446 Urea is the principle which confers upon urine its chief peculiarities. 1862Huxley Lect. Working Men 72 Urea..forms one of the waste products of animal structures. 1878Kingzett Anim. Chem. 190 Urea was discovered by Boerhaave before 1720, and was called by him the essential salt of urine.
b. A urea-formaldehyde plastic or resin.
1935Economist 7 Dec. 1142/2 Phenolic plastics are used for various mouldings, urea is translucent plastic. 1961H. R. Symonds Source Bk. New Plastics II. ii. 32 A new urea especially prepared for the bonding of particle board. 1969L. K. Arnold Introd. Plastics vi. 83 The ureas are somewhat more expensive [than the phenolics] but have the advantage of being available in a wide range of light colors.
2. attrib. and Comb., as urea excretion, urea-formation, urea-residue; urea-formaldehyde, used attrib. and absol. to designate plastics, resins, etc., made by condensation of urea with formaldehyde; urea nitrate, oxalate (see quots. 1873); urea resin, a synthetic resin derived from urea; a urea-formaldehyde resin.
1866Odling Anim. Chem. 129 The assumption of pre-existent urea-residues in uric acid. 1873C. H. Ralfe Phys. Chem. 83 Urea oxalate (2CN2H4O,C2H2O4): the crystals form long, transparent, tufted laminæ. Ibid., Urea nitrate (CN2H4O,HNO3): the crystals form shining, rhombic plates. 1897Allbutt's Syst. Med. IV. 292 Observations on the urea excretion. Ibid. 72 Pointing to the liver as the chief seat of urea-formation. 1928Brit. Patent 291,473 3/2 When using urea-formaldehyde resins, alkaline catalysts may be used to obtain the intermediate condensation product. 1933[see phenolformaldehyde s.v. phenol c]. 1937R. S. Morrell et al. Synthetic Resins ii. 52 Tootal, Broadhurst, Lee Company Limited have patented the use of urea resins to prevent the crushing of cellulosic fabrics. 1975M. P. Stevens Polymer Chem. xii. 329 Decorative interior plywood is normally glued with urea resin because the dark-colored phenolic resins can stain the veneer. 1976Milton Keynes Express 9 July 14/4 The majority of houses have cavity walls and these can be insulated by filling the cavity with..a foaming resin called urea formaldehyde. 1984Christian Science Monitor 2 Mar. 23/1 The safety of urea-formaldehyde insulation..has been a subject of debate for years. |