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Urea-formaldehyde (UF), also known as urea-methanal, so named for its common synthesis pathway and overall structure, [1] is a nontransparent thermosetting resin or polymer. It is produced from urea and formaldehyde. These resins are used in adhesives, plywood, particle board, medium-density fibreboard (MDF), and molded objects.
It is produced by the condensation reaction of isobutyraldehyde and two equivalents of urea: (CH 3 ) 2 CHCHO + 2 OC(NH 2 ) 2 → (CH 3 ) 2 CHCH{NHC(O)NH 2 } 2 + H 2 O The controlled-release process is the reverse of the above reaction, which only occurs after the IBDU dissolves.
Traders attempt to identify market trends using technical analysis, a framework which characterizes market trends as predictable price tendencies within the market when price reaches support and resistance levels, varying over time. A future market trend can only be determined in hindsight, since at any time prices in the future are not known.
Sensitization to formaldehyde has been decreasing since 1980 due in part to the replacement of formaldehyde by these formaldehyde releasers. [2] As of 2009, frequency of sensitization to formaldehyde is stable at 2–3% in Europe. [2] It might be as high as 9% in the USA. [2] [13]
Some people have a contact allergy to imidazolidinyl urea causing dermatitis. [3] Such people are often also allergic to diazolidinyl urea. In addition to being an allergen, it is a formaldehyde releaser, since it generates formaldehyde slowly as it degrades. Although the formaldehyde acts as a bactericidal preservative, it is a known carcinogen.
Formaldehyde is a common precursor to more complex compounds and materials. In approximate order of decreasing consumption, products generated from formaldehyde include urea formaldehyde resin, melamine resin, phenol formaldehyde resin, polyoxymethylene plastics, 1,4-butanediol, and methylene diphenyl diisocyanate. [40]
The structure of the molecule of urea is O=C(−NH 2) 2.The urea molecule is planar when in a solid crystal because of sp 2 hybridization of the N orbitals. [8] [9] It is non-planar with C 2 symmetry when in the gas phase [10] or in aqueous solution, [9] with C–N–H and H–N–H bond angles that are intermediate between the trigonal planar angle of 120° and the tetrahedral angle of 109.5°.
Volume–price trend (VPT) (sometimes price–volume trend) is a technical analysis indicator intended to relate price and volume in the stock market.VPT is based on a running cumulative volume that adds or subtracts a multiple of the percentage change in share price trend and current volume, depending upon the investment's upward or downward movements.