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Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer. It has the idealized formula [CH 2 CH(OH)] n. It is used in papermaking, textile warp sizing, as a thickener and emulsion stabilizer in polyvinyl acetate (PVAc) adhesive formulations, in a variety of coatings, and 3D printing. It is colourless (white) and odorless.
Some grades of polyvinyl alcohol and other water-soluble polymers can promote emulsion polymerization even though they do not typically form micelles and do not act as surfactants (for example, they do not lower surface tension). It is believed that growing polymer chains graft onto these water-soluble polymers, which stabilize the resulting ...
Solution styrene-butadiene rubber (sSBR) is produced by anionic polymerization in hydrocarbons leading to rubber with better properties for making tires than emulsion polymerization type. Polyvinyl acetate used further for polyvinyl alcohol is manufactured by radical polymerization in methanol solution.
The degree of polymerization of polyvinyl acetate is typically 100 to 5000, while its ester groups are sensitive to base hydrolysis and slowly convert PVAc into polyvinyl alcohol and acetic acid. The glass transition temperature of polyvinyl acetate is between 30 and 45 °C depending on the molecular weight.
Vinyl polymers are subject of several structural variations, which greatly expands the range of polymers and their applications. With the exception of polyethylene, vinyl polymers can arise from head-to-tail linking of monomers, head-to-head combined with tail-to-tail, or a mixture of those two patterns. Additionally the substituted carbon center in such polymers is stereogenic (a "chiral center")
Vinyl acetate is the acetate ester of vinyl alcohol. Since vinyl alcohol is highly unstable (with respect to acetaldehyde), the preparation of vinyl acetate is more complex than the synthesis of other acetate esters. The major industrial route involves the reaction of ethylene and acetic acid with oxygen in the presence of a palladium catalyst. [6]
At room temperature, acetaldehyde (H 3 CC(O)H) is more stable than vinyl alcohol (H 2 C=CHOH) by 42.7 kJ/mol. [3] Vinyl alcohol gas isomerizes to the aldehyde with a half-life of 30 min at room temperature. [1] H 2 C=CHOH → H 3 CC(O)H The industrial synthesis of acetaldehyde (Wacker process) proceeds via the intermediacy of a vinyl alcohol ...
Polyvinylpyrrolidone (PVP), also commonly called polyvidone or povidone, is a water-soluble polymer compound made from the monomer N-vinylpyrrolidone. [1] PVP is available in a range of molecular weights and related viscosities, and can be selected according to the desired application properties. [2]