| abstract |
Oil soluble grafted ethylene-alpha-olefin copolymer useful as a viscosity modifier for oleaginous compositions comprising:n (i) backbone copolymer of ethylene and at least one other alpha-olefin monomer, said copolymer comprising intramolecularly heterogeneous copolymer chains containing at least one crystallizable segment of methylene units and at least one low crystallinity ethylene-alpha-olefin copolymer segment, wherein said at least one crystallizable segment comprises at least about 10 weight percent of said copolymer chain and contains at least about 57 weight percent ethylene, wherein said low crystallinity segment contains not greater than about 53 weight percent ethylene, and wherein said copolymer has a molecular weight distribution characterized by at least one of a ratio of M w /M n of less than 2 and a ratio of M z /M 2 of less than 1.8, and wherein at least two portions of an individual intramolecularly heterogeneous chain, each portion comprising at least 5 weight percent of said chain, differ in composition from one another by at least 7 weight percent ethylene; having grafted on said backbone copolymer (ii) residue of ethylenically unsaturated grafting material; said grafted ethylenealpha-olefin copolymer having substantially the molecular weight distribution, i.e., within about 10 percent, of said copolymer of ethylene. The preferred grafting material is an ethylenically monounsaturated carboxylic acid material having 1 to 2 carboxylic acid groups or an anhydride group. |