Polyolefin-Based Crosslinked Compositions and Methods of Making Them

A method for making a crosslinked composition comprising the steps of:

• (a) providing a composition comprising:
• (i) at least one propylene-based polymer comprising propylene-derived units and optionally one or more dienes, the propylene-based polymer having a triad tacticity of from 50% to 99% and a heat of fusion of less than 80 J/g;
• (ii) from about 0.1 to about 5 wt % of at least one ultraviolet photoinitiator selected from the group consisting of a benzophenone photoinitiator;
• a phenylglyoxylate photoinitiator;
• an alpha hydroxy ketone photoinitiator;
• a combination of acyl phosphine oxide and an alpha hydroxy ketone photoinitiator;
• 2,2-aimethoxy-1,2-diphenylethan-1-one;
• and a combination of oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester;
• (b) extruding the composition;
• and
• (c) crosslinking the composition using ultraviolet radiation.

A method for making a crosslinked composition comprising the steps of:

• (a) providing a composition comprising:
• (i) from about 60 to about 95 wt % of at least one propylene-based polymer comprising propylene-derived units and one or more dienes, the propylene-based polymer having a triad tacticity of from 50% to 99% and a heat of fusion of less than 80 J/g;
• (ii) from about 1 to about 20 wt % of a at least one of a polypropylene homopolymer and polypropylene-ethylene copolymer;
• and
• (iii) from about 0.1 to about 5 wt % of at least one ultraviolet photoinitiator;
• (b) extruding the composition;
• and
• (c) crosslinking the composition using ultraviolet radiation.