Shoe midsole

A method for preparing a shoe midsole composed of a foamed peroxide-crosslinked polyolefin elastomer, the method comprising:

• forming a Component A including a mixture of a first silane-grafted polyolefin and a second silane-grafted polyolefin;
• forming a masterbatch (Component B) including a blowing agent, a peroxide, additives, and an elastomer component that includes one or more elastomeric polymers selected from the group consisting of ethylene vinyl acetate copolymer, polyolefin elastomers, olefin block copolymer, polyoctenamer, anhydride modified ethylene copolymers, ethylene propylene diene terpolymer, and combinations thereof, and
• mixing Component A and Component B to form a reactive mixture;
• and
• reacting the reactive mixture for a predetermined time period under moisture-free conditions at a reaction temperature to form the foamed peroxide-crosslinked polyolefin elastomer such that the first silane-grafted polyolefin is crosslinked to the second silane-grafted polyolefin and to the elastomer component with C—C bonds and the second silane-grafted polyolefin is crosslinked to the elastomer component with C—C bonds and such that the foamed peroxide-crosslinked polyolefin elastomer includes a plurality of closed cells, the foamed peroxide-crosslinked polyolefin elastomer being substantially free of silane crosslinking as formed and substantially free of water, wherein the ethylene propylene diene terpolymer is in sufficient amount that a melting temperature of the foamed peroxide-crosslinked polyolefin elastomer is greater than 100° C. as measured by differential scanning calorimeter thermographs.

A masterbatch for forming a midsole composed of a foamed peroxide-crosslinked polyolefin elastomer, the masterbatch comprising:

• a blowing agent;
• a peroxide;
• additives;
• and
• an elastomer component that includes one or more elastomeric polymers selected from the group consisting of ethylene vinyl acetate copolymer, polyolefin elastomers, olefin block copolymer, polyoctenamer, anhydride modified ethylene copolymers, ethylene propylene diene terpolymer, and combinations thereof, the masterbatch being adapted to be combined (e.g., mixed) with a Component A under moisture-free conditions to form a reactive mixture, the Component A including a mixture of a first silane-grafted polyolefin and a second silane-grafted polyolefin and optionally one or more additional silane-grafted polyolefins, wherein the reactive mixture is reacted for a predetermined time period under moisture-free conditions at a reaction temperature to form the foamed peroxide-crosslinked polyolefin elastomer such that the first silane-grafted polyolefin is crosslinked to the second silane-grafted polyolefin and to the elastomer component with C—C bonds and the second silane-grafted polyolefin is crosslinked to the elastomer component with C—C bonds and such that the foamed peroxide-crosslinked polyolefin elastomer includes a plurality of closed cells, the foamed peroxide-crosslinked polyolefin elastomer being substantially free of silane crosslinking as formed and substantially free of water, wherein the ethylene propylene diene terpolymer is in sufficient amount that a melting temperature of the foamed peroxide-crosslinked polyolefin elastomer is greater than 100° C. as measured by differential scanning calorimeter thermographs.