Thermal grease based on hyperbranched olefinic fluid

A process to prepare a thermal grease composition comprising

• (a) contacting together ethylene, and optionally propylene, and further optionally, an alpha-olefin,
• and at least one coordination-insertion catalyst,
• wherein the coordination-insertion catalyst is a metal-ligand complex wherein the metal is selected from zirconium, hafnium and titanium,
• and has an ethylene/octene reactivity ratio up to 20, and a kinetic chain length up to 20 monomer units;
• in a continuously-fed backmixed reactor zone under conditions such that a mixture of at least two products is formed, the mixture including
• (i) a hyperbranched oligomer
• having an average of at least 1.5 methine carbons per oligomer molecule,
• and having at least 40 methine carbons per one-thousand total carbons, and
• wherein at least 40 percent of the methine carbons is derived from the ethylene or, where the optional propylene is included, from the ethylene and the propylene, and
• wherein the average number of carbons per molecule is from 25 to 200;
• and
• (ii) at least one organic volatile product having an average number of carbons per molecule that is less than or equal to 14;
• (b) separating the hyperbranched oligomer from the organic volatile product;
• (c) recovering the hyperbranched oligomer;
• and
• (d) admixing the hyperbranched oligomer and a thermally conductive filler to form a thermal grease composition.