Polyvinyl acetate (PVA, PVAc, poly(ethenyl ethanoate)), commonly known as wood glue (a term that may also refer to other types of glues), PVA glue, white glue, carpenter's glue, school glue, or Elmer's Glue in the US, is a widely available adhesive used for porous materials like wood, paper, and cloth. An aliphatic rubbery synthetic polymer with the formula (C4H6O2)n, it belongs to the polyvinyl ester family, with the general formula −[RCOOCHCH2]−. It is a type of thermoplastic.

Properties

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. PVAc dispersions such as Elmer's Glue-All contain polyvinyl alcohol as a protective colloid. In alkaline conditions, boron compounds such as boric acid or borax cause the polyvinyl alcohol to cross-link, forming tackifying precipitates or toys, such as Slime and Flubber. A number of microorganisms can degrade polyvinyl acetate. Most commonly, damage is caused by filamentous fungi; however, algae, yeasts, lichens, and bacteria can also degrade polyvinyl acetate.

Discovery

Polyvinyl acetate was discovered in Germany in 1912 by Fritz Klatte. The monomer, vinyl acetate, was first produced on an industrial scale by the addition of acetic acid to acetylene with a mercury(I) salt, but it is now primarily made by palladium-catalyzed oxidative addition of acetic acid to ethylene.

Preparation

PVA is a vinyl polymer. Polyvinyl acetate is prepared by the polymerization of vinyl acetate monomer (free-radical vinyl polymerization of the monomer vinyl acetate).

Applications

As a dispersion in water (usually an emulsion), PVAc preparations are used as adhesives for porous materials, particularly for wood, paper, and cloth, and as a consolidant for porous building stone, in particular sandstone. PVAc is considered a food-safe material, and is thus used often in such applications (e.g., in food packaging material). Uses: The stiff homopolymer PVAc, but mostly the softer copolymer, a combination of vinyl acetate and ethylene, vinyl acetate ethylene (VAE), is also used in paper coatings, paint and other industrial coatings, as a binder in nonwovens in glass fibers, sanitary napkins, filter paper and in textile finishing. Polyvinyl acetate is also the raw material to make other polymers like: