30 августа, 2015 
Malyar Ken Geddes
Crown Berger Limited, Darwen, Lancashire, England
Poly(vinyl acetate) (PVA) and ethylene-vinyl acetate (EVA) copolymer adhesives have much in common, yet represent extremes in the degree of sophistication of their production processes. Both products are stable suspensions in water of a film-forming polymer, the particles of which are generally spherical. They are made by emulsion polymerization, which uses a free-radical addition mechanism to polymerize the monomer in the presence of water and stabilizers. Vinyl acetate is the sole or major monomeric raw material.
The major difference between the processes is the incorporation in EVAs of ethylene, an internally plasticizing monomer. The use of ethylene requires production equipment suitable for safe handling of a highly flammable, high-pressure gas. Despite the volatility and very low flash point of vinyl acetate, simple PVAs are manufactured successfully by many small-scale producers in developing countries; EVAs are made only at sophisticated and costly plants where ethylene gas, engineering skills, and a significant demand for the product come together.
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