Abstract: Foamed thermoplastic polyolefin elastomer is formed by heating a foamable thermoplastic polyolefin elastomer-containing polymeric composition containing each of a first water-releasing blowing agent which is at least one of metal hydroxide and water hydrate of a salt of a metal of Group 1 or Group 2 of the Periodic Table and a second blowing agent which is neither a metal hydroxide nor a water hydrate of a salt of a metal of Group 1 or Group 2 of the Periodic Table, to a temperature above the melting point of the polyolefin elastomer. The second blowing agent may be a chemical blowing agent and may release, water, a mixture of water and carbon dioxide or another gas, including carbon monoxide, carbon dioxide, and nitrogen.

Abstract: The invention relates to a process for preparing a foamed polymeric article, comprising heating a polymeric composition, said composition comprising a thermoplastic polyolefin elastomer, a first blowing agent in the form of a water releasing chemical compound, and a second, different blowing agent, to a temperature at which the first blowing agent releases water, to foam said thermoplastic polyolefin elastomer, said temperature being above the melting point of the thermoplastic polyolefin elastomer, characterized in that said first blowing agent comprises a metal hydroxide, a metal salt of Group 1 or 2 of the Periodic Table containing hydrate water and mixtures thereof and said second blowing agent not being a metal hydroxide or a Group 1 or 2 of the Periodic Table metal salt containing hydrate water.