Poly vinyl acetate and related polymers

In this chapter poly(vinyl acetate) and some vinyl acetate copolymers are described. The important copolymers, ethylene-vinyl acetate and vinyl chloride-vinyl acetate have been dealt with in Chapters 2 and 4 respectively. Also considered are poly(vinyl alcohol) and poly(vinyl acetal)s, which are derivatives of poly(vinyl acetate). 

At the present time, the most widely used industrial preparation of vinyl acetate is from acetylene and acetic acid  

Further reaction can occur between vinyl acetate and acetic acid to give ethylidene diacetate  

Formation of this by-product is minimized by using a molar excess of acetylene, short reaction times and low temperatures. 

The reaction may be carried out in the vapour or liquid phase, the former being generally preferred for industrial processes. In a typical vapour phase preparation, a mixture of acetylene (in excess) and acetic acid vapour is passed through a reaction tube at 190—220°C. The tube contains a catalyst such as zinc acetate or zinc silicate and about 50% of the acetic acid is converted per pass. The exit vapours are cooled acetylene is recycled and the liquid stream is distilled to give vinyl acetate and acetic acid, which is also recycled. 

Until the mid-1960s, vinyl acetate manufacture was based almost entirely on acetylene. Since that time, however, more economical ethylene-based processes have been developed and now very few manufacturers use the acetylene route. 

Initially, liquid phase processes were developed but because of severe corrosion problems, gas-phase processes are now more common. Typically, a mixture of ethylene and acetic acid is oxidized over a palladium catalyst at 0.5-1 MPa (5-10 atmospheres) and 150-200°C. The exit gases are quenched and vinyl acetate is separated by distillation. A yield of about 95% is obtained. 

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Biodegradability of Poly (vinyl acetate) and Related Polymers... 

M. Amann and O. Minge, "Biodegradability of poly(vinyl acetate) and related polymers," in B. Rieger, A. Kiinkel, G.W. Coates, R. Reichardt, E. Dinjus, and T.A. Zevaco, eds.. Synthetic Biodegradable Polymers, Vol. 245 of Advances in Polymer Science, pp. 137-172. Springer-Verlag, November 2012. 

POLY(VINYL ACETATE) AND RELATED POLYMERS 15.9.1 Poly(vinyl acetate) and Ethylene/Vinyl Acetate Copolymers... 

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