SHOE SOLES, COMPOSITIONS, AND METHODS OF MAKING THE SAME

1 . A shoe midsole comprising:

a foamed silane-crosslinked polyolefin elastomer having a density less than 0.50 g/cm 3 , the foamed silane-crosslinked polyolefin elastomer comprising:

a first polyolefin having a density less than 0.86 g/cm 3 ,

a second polyolefin having a crystallinity less than 40%,

a silane crosslinker,

a grafting initiator,

a condensation catalyst, and

a foaming agent,

wherein the shoe midsole exhibits a compression set of from about 1.0% to about 50.0%, as measured according to ASTM D 395 (48 hrs @ 50° C.).

2 . The shoe midsole of claim 1 , wherein the first polyolefin is an ethylene/α-olefin copolymer from about 60 wt % to about 97 wt %.

3 . The shoe midsole of claim 1 , wherein the second polyolefin is a polypropylene homopolymer and/or a poly(ethylene-co-propylene), the second polyolefin from about 10 wt % to about 35 wt %.

4 . The shoe midsole of claim 1 , wherein the silane crosslinker comprises a vinyltrialkoxy silane from about 1 wt % to about 4 wt %.

5 . The shoe midsole of claim 1 , wherein the grafting initiator comprises one or more halogen molecules, azo compounds, carboxylic peroxyacids, peroxyesters, peroxyketals, and peroxides, the grafting initiator from greater than 0.15 wt % to about 2 wt %.

6 . The shoe midsole of claim 1 , wherein the condensation catalyst comprises a sulfonic ester catalyst and/or a tin catalyst from about 1 wt % to about 4 wt %.

7 . The shoe midsole of claim 1 , wherein the density of the foamed silane-crosslinked polyolefin elastomer is less than about 0.35 g/cm 3 .

8 . The shoe midsole of claim 1 , wherein the shoe midsole exhibits an Asker C hardness of from about 20 to about 60.

9 . The shoe midsole of claim 1 , further comprising:

a coloring agent.

10 . The shoe midsole of claim 1 , wherein the shoe midsole exhibits a rebound resilience of at least 60%.

11 . A shoe sole comprising:

a composition comprising a foamed silane-crosslinked polyolefin elastomer having a density less than 0.88 g/cm 3 ,

wherein the shoe sole exhibits a compression set of from about 1.0% to about 50.0%, as measured according to ASTM D 395 (48 hrs @ 50° C.).

12 . The shoe sole of claim 11 , wherein the density of the foamed silane-crosslinked polyolefin elastomer is less than about 0.50 g/cm 3 .

13 . The shoe sole of claim 11 , wherein the shoe sole exhibits an Asker C hardness of from about 20 to about 60.

14 . The shoe sole of claim 11 , wherein the compression set is from about 15.0% to about 20.0%.

15 . The shoe sole of claim 11 , further comprising:

a coloring agent.

16 . The shoe sole of claim 11 , wherein the foamed silane-crosslinked polyolefin elastomer comprises a first polyolefin having a density less than 0.86 g/cm 3 , a second polyolefin having a crystallinity less than 40%, a silane crosslinker, a grafting initiator, a condensation catalyst, and a foaming agent.

17 . The shoe sole of claim 11 , wherein the shoe sole exhibits a rebound resilience of at least 60%.

18 . The shoe sole of claim 11 , wherein the density of the foamed silane-crosslinked polyolefin elastomer is less than about 0.35 g/cm 3 .

19 . A footwear article, comprising:

a shoe sole and/or a shoe midsole,

wherein each of the shoe sole and the shoe midsole comprises:

a first polyolefin having a density less than 0.86 g/cm 3 ,

a second polyolefin having a crystallinity less than 40%,

a silane crosslinker,

a grafting initiator,

a condensation catalyst, and

a foaming agent, and

further wherein each of the shoe sole the shoe midsole exhibits a compression set of from about 1.0% to about 50.0%, as measured according to ASTM D 395 (48 hrs @ 50° C.).

20 . The footwear article of claim 19 , wherein the first polyolefin is an ethylene/α-olefin copolymer from about 60 wt % to about 97 wt %.