Peroxide containing polyolefin formulation

A method of chemically modifying a polyolefin formulation in such a way as to modify melt viscosity thereof without completely curing the polyolefin formulation, which comprises, prior to the chemical modification, from 60 to 99.45 weight percent (wt %) of (A) an ethylenic-based (co)polymer composition consisting essentially of an ethylenic-based (co)polymer or a combination of the ethylenic-based (co)polymer and a polypropylene polymer, with the proviso that the polypropylene polymer is from 0 to <40 wt % of the polyolefin formulation;

• from 0.05 to less than 2.00 wt % of (B) an antioxidant;
• and from 0.15 to 1.00 weight percent (wt %) of (C) a first organic peroxide having a 1-hour half-life temperature of less than or equal to 155 degrees Celsius (° C.) and/or a 10-hour half-life temperature of less than or equal to 135° C., when measured according to the Half-Life Temperature Test Method;
• wherein all weight percents are based on total weight of the polyolefin formulation;
• the method comprising heating a melt of the polyolefin formulation, which has been kept at a temperature less than 160.0° C., to a temperature of greater than or equal to 160.0° C., thereby decomposing the (C) first organic peroxide in the melt so as to chemically modify melt viscosity of the polyolefin formulation to give a first intermediate composition having a melt viscosity that is greater than the melt viscosity of the polyolefin formulation, all without completely curing the polyolefin formulation or the first intermediate composition;
• wherein the melt of the polyolefin formulation comprises a melt of the (A) ethylenic-based (co)polymer composition in contact with the (B) antioxidant and the (C) first organic peroxide;
• and
• further comprising contacting the first intermediate composition with from 0.05 to 3.0 wt % of (D) a second organic peroxide having a 1-hour half-life temperature of less than or equal to 155° C. and/or a 10-hour half-life temperature of less than or equal to 135° C., when measured according to the Half-Life Temperature Test Method, described later, to give a second intermediate composition comprising the first intermediate composition and the (D) second organic peroxide.