| 摘要 |
The present invention relates to an ethylene homo or copolymer having a density of between 0.923 and 0.935 g/cm3, having a molecular weight distribution Mw/Mn of between 3 and 10, and comprising from 0.10 to 0.50 wt. percent of units derived from a carbonyl group containing compound, based on the total weight of the homo or copolymer. In addition, the invention relates to a free radical initiation polymerization process for the preparation of medium density ethylene polymers or copolymers, comprising reacting ethylene and optionally one or more comonomers at a high pressure, conveniently between 1600 and 4000 kg/cm2, and at temperatures of about 150-330 ~C in a reactor system consisting of at least one autoclave reactor or of a combination of autoclave and tubular reactors, in the presence of free radical initiators and a carbonyl group containing compound. Finally, the invention relates to carbonyl group containing chain transfer agents to obtain improved polymer processing and performance properties in flat die extrusion processes and applications.
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