Abstract: An improvement in a process for the preparation of an ethylene homopolymer or a copolymer of ethylene with an .alpha.-olefin containing 3 to 15 carbon atoms by contacting the monomer or mixture of monomers in solution, suspension or in gas phase at 20.degree. to 250.degree. C. at a pressure of 1 to 50 bar with a mixed catalyst comprising a chlorine containing titanium (III) compound and an organoaluminum compound in the presence of hydrogen, the improvement residing in employing as the organoaluminum compound a trialkylaluminum compound in an amount of 0.1 to 20 mol per mol titanium (III) compound and including in the polymerization mixture oxygen at a concentration of 0.001 to 0.1 volume percent based upon the amount of ethylene. By carrying out the polymerization by including oxygen in the polymerization reaction mixture and employing trialkylaluminum compound as the organoaluminum compound the mean molecular weight of the polymer can be regulated while obtaining a desired molecular weight distribution.

Abstract: A high molecular weight copolymer of ethylene and a C.sub.3 -C.sub.20 .alpha.-olefin which, after being molded at room temperature and pressure-free tempered at 120 to 250.degree. C. and thereafter cooled, provides molded articles having an ultimate tensile strength of more than 200 kg per square centimeter measured at 120.degree. C. and an impact strength of more than 200 kg cm/cm.sup.2 measured at 23.degree. C.; a process for the preparation of such a copolymer by a Ziegler catalysis which process is characterized in that the catalyst which is employed is one obtained by reducing a titanium-(IV)-halide with an organo-aluminum compound in an inert solvent such that the concentration of titanium-(III)-halide so formed amounts to 30 to 200 m mol/liter solvent, the C.sub.3 -C.sub.20 .alpha.-olefin is employed in an amount of 0.05 to 5 weight percent based upon the weight of the ethylene and the catalyst is either initially contacted with C.sub.3 -C.sub.20 .alpha.

Abstract: A phenol/formaldehyde condensation product of a 4,4'-thio-bis-(dialkylphenol) and formaldehyde having a molecular weight of 1,000 to 4,000; a process for preparing such a condensation product by contacting 4,4'-thio-bis-(dialkylphenol) and a source of formaldehyde in the presence of a protonic acid catalyst; and the use of such a condensation product as an antioxidant in an olefin polymer or copolymer composition.

Abstract: A process is described whereby corrosive, halogen-containing compounds are removed from polyolefins. Briefly, the process comprises mixing the polyolefin with water in a purification zone, treating at least part of the water with an ion exchanger and returning the treated water to the purification zone.

Abstract: A phenol/formaldehyde condensation product of a 4,4'-thio-bis-(dialkylphenol) and formaldehyde having a molecular weight of 1,000 to 4,000; a process for preparing such a condensation product by contacting 4,4'-thio-bis-(dialkylphenol) and a source of formaldehyde in the presence of a protonic acid catalyst; and the use of such a condensation product as an antioxidant in an olefin polymer or copolymer composition.

Abstract: An olefin polymerization catalyst comprising a chromium compound deposited on a carrier, which chromium compound is complexed with a straight-chain, branched-chain, or cyclic aliphatic hydrocarbon or mixture thereof such that the mol ratio of aliphatic hydrocarbon to chromium compound is 1:2-3, said chromium compound being deposited on said carrier material in an amount between 10.sup..sup.-3 and 10 millimols chromium compound per gram of carrier material, said carrier material also containing a trialkyl, tricycloalkyl, triaryl, monohalodihydrocarbyl, or monoalkoxydihydrocarbyl aluminum compound; a process for preparing such an olefin polymerization catalyst and the use of such catalyst in the polymerization of olefins, particularly ethylene, propylene, 2-methylpropylene and butene-1.