Abstract: The invention relates to a process for the continuous preparation of ethylene homopolymers or copolymers in the presence of free-radical polymerization initiators and, if desired, molecular weight regulators at from 120° C. to 350° C. and pressures in the range from 100 to 4000 bar, in which the polymer is separated from unpolymerized ethylene in a high-pressure stage at a pressure of from 100 to 500 bar and at least one low-pressure stage at a pressure of from 1 to 100 bar and the ethylene separated off in the high-pressure stage is separated from remaining monomeric, oligomeric and/or polymeric constituents and recirculated to the inlet of the tube reactor in a high-pressure circuit and the ethylene separated off in the low-pressure stage is separated from remaining monomeric, oligomeric and/or polymeric constituents and recirculated to the inlet of the tube reactor in a low-pressure circuit. The initiator is used as a solution in an isoparaffinic solvent having a boiling point of not more than 160° C.

Abstract: In composite elements which have the following layer structure: (i) from 2 to 20 mm of metal, plastic or wood, (ii) from 10 to 300 mm of plastic and (iii) from 2 to 20 mm of metal, plastic or wood, hollow bodies having an external diameter of less than 5 mm are present in the layer (ii).

Abstract: Ethylene homopolymers and copolymers are prepared in a tube reactor at from 160° C. to 350° C.

Abstract: A process for preparing ethylene polymers by the high-pressure method comprises dissolving one or more free-radical initiators in one or more ketones of the formula I 1