Abstract: This invention relates to entirely novel compositions comprisingA. high-molecular anions from dissociation of a part or the whole of the carboxylic group of a conjugated diene-maleic acid derivative copolymer with repeating units represented by the formulae ##STR1## WHEREIN R represents a conjugated diene unit in the copolymer, R' and R" each represent hydrogen or an organic radical having from 1 to 18 carbon atoms and p and q each are an integer;B. one or more cations of alkali metal cations selected from the group consisting of Na.sup.+, K.sup.+ and Li.sup.+ and quaternary ammonium cations represented by the formula R.sub.1 R.sub.2 N.sup.+ R.sub.3 R.sub.4 wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each are selected from the group consisting of hydrogen, alkyl radical of from 1 to 18 carbon atoms, cycloalkyl radical and aryl radical;C. mg.sup.2+ ;D. anion of magnesium compound(s) or alkali metal compound(s) represented by X.sup.n- wherein n is an integer 1 or 2; andE.

Abstract: Processes for the production of polyolefins are disclosed in which olefins are polymerized in the presence of Ziegler catalyst components carried on magnesium oxide. The polymerization is effected in the presence of a solid catalyst comprising a transition metal halide carried on magnesium oxide, such oxide having been pretreated with an organic halide, and another catalyst component selected from the group consisting of organoaluminum compounds and alkylzinc. The combination of these catalysts contributes to increased polymer yields based on both carrier and transition metal.