COPOLYMERIZATION OF ETHYLENE AND VINYL-ACETATE UNDER HIGH-PRESSURE WITH A PEROXIDE TRIETHYLALUMINIUM SYSTEM/

The present study was carried out to examine the effectiveness of an a ddition of triethylaluminium to tert-butyl perpivalate which is freque ntly used in industrial applications for initiating the copolymerisati on of ethylene with vinyl acetate. For this purpose, polymerisation te sts were carried out in the laboratory on a continuous basis at 1900 b ar and 150 degrees C. Vinyl acetate was added in concentrations of up to 36 wt.-% in the feed to the reactor. The organic peroxide concentra tion was 50 mole ppm; the concentration of organoaluminium alkyl was v aried within the range of 0-75 mole ppm. The effects observed, namely an increase in the conversion and a decrease in the peroxide consumpti on were more marked than with the homopolymerisation of ethylene. This is attributable to the increased rate of chain growth in addition to the increased amount of radicals available. The properties of the copo lymers obtained are changed only moderately by aluminium alkyl. Apart from a decrease in density and an increase in the melting point, a dec rease in the polydispersity was observed.