Composition comprising semi-crystalline polyolefin and sulfonyl-azide, resulting foams and methods of making the same

A foam comprising:

• a semi-crystalline polypropylene having a crystallinity of 50% to 80% and coupled with a poly(sulfonyl azide) of at least 500 ppm, based on the total weight of the foamable composition,
• wherein the semi-crystalline polypropylene coupled with a poly(sulfonyl azide) has a melt strength of at least 20 cN, a melt drawability of at least 100 mm/s, and the foam is a low density foam having a density in the range from 0.005 g/cm3 to 0.6 g/cm3, and wherein the semi-crystalline polypropylene is a polypropylene homopolymer.

A method of preparing a foam comprising:

• mixing a foamable composition, comprising a semi-crystalline polypropylene having a crystallinity of 50% to 80% and a poly(sulfonyl azide) of at least 500 ppm, through a single extrusion step, having a melt strength of at least 20 cN, and a melt drawability of at least 100 mm/s, and wherein the semi-crystalline polypropylene is a polypropylene homopolymer.