Copolymerisation of ethylene and vinyl acetate under high pressure with a peroxide/triethylaluminium system

Abstract

The present study was carried out to examine the effectiveness of an addition of triethylaluminium to tert-butyl perpivalate which is frequently used in industrial applications for initiating the copolymerisation of ethylene with vinyl acetate. For this purpose, polymerisation tests were carried out in the laboratory on a continuous basis at 1900 bar and 150°C. Vinyl acetate was added in concentrations of up to 36 wt.-% in the feed to the reactor. The organic peroxide concentration was 50 mole ppm; the concentration of organoaluminium alkyl was varied within the range of 0-75 mole ppm.The effects observed, namely an increase in the conversion and a decrease in the peroxide consumption 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 copolymers obtained are changed only moderately by aluminium alkyl. Apart from a decrease in density and an increase in the melting point, a decrease in the polydispersity was observed. CCC 0003-3146/96/$07.00 87 G. Luft, M. Jabbari, M. Dorn len. Dies wird auf die zusatzliche Steigerung der Reaktionsgeschwindigkeit des Kettenwachstums neben dem erhohten Radikalangebot zuriickgefuhrt.Die Eigenschaften der erhaltenen Copolymeren werden durch das Triethylaluminium nur moderat verandert. Neben einer Abnahme der Dichte und einer Zunahme des Schmelzpunkts wurde eine Vemngerung der Polydispersitat beobachtet.

Modeling of ethylene copolymerization in nonisothermal high‐pressure reactors using bifunctional initiators

“…The polymer kinetics model and flow reactor model were integrated together, and then solved using a variable order solver based on numerical differentiation formulas (NDFs) for stiff differential equations in Matlab environment. The rate constants of ethylene and butyl‐acrylate reported in Tables and were taken from previous studies . Variations of the physical and transport properties of the reaction mixture and, the heat transfer coefficients were updated using correlations in Table .…”

Controlled copolymerization of vinyl acetate with 1‐alkenes and their fluoro derivatives by degenerative transfer

“…The uncontrolled radical copolymerization of VAc with ethene under high temperature and very high pressure is well documented 28, 29. Recently, Matyjaszewski has reported the controlled homopolymerization of VAc by degenerative transfer (DT), which involves reversible halogen exchange between a dormant species and a growing radical chain (Scheme ) 27.…”

“…The VAc/ethene copolymers are still produced exclusively by uncontrolled radical polymerization at high temperature and very high pressure 28, 29. Earlier reports on copolymerizations under mild conditions initiated by either AIBN30 or a combination of trialkylaluminum‐Lewis base‐peroxide claimed the formation of polymers with relatively low molecular weight ( M n ≤ 8000) 31.…”

Starve fed emulsion copolymerization of vinyl acetate and 1‐hexene at ambient pressure

“…There is a body of literature dealing with the copolymerization of VAc with α ‐olefins . However, despite the great interest generated in copolymers of VAc and α ‐olefins, most investigations have been limited to the copolymerization of VAc with ethylene, and other α ‐olefins have been disregarded.…”