Ethylene-hexene-1 copolymers through modified phillips catalysis

Copolymerization of ethylene and hexene has been carried out using Phillips' catalysts (chromium oxide deposited on silica) modified with small amounts of triethylaluminium Al(C₂H₅)₃], without solvent other than hexene itself and under constant ethylene pressure. The copolymers are highly disperse, not only in molecular weight but also in composition; the amount of hexene incorporated in the solid fraction is always less than 4%. Most of the hexene units are in a waxy fraction, which may account for a very high proportion of the copolymer produced. The behaviour of the catalyst is strongly dependent upon the amount of Al(C₂H₅)₃ used.