Articles that include a polymer foam and methods for preparing them.

A method for preparing a polymer foam, said method comprising: (a) providing a plurality of expandable polymeric microspheres and a polymer melt composition containing less than 20 wt% solvent, each polymeric microsphere expansible a polymer shell and a material central as a gas, a liquid, or a combination thereof, that expands upon heating, causing, in turn, that the expansion of the core material to expand bark; (B) melt mixing the molten polymer composition and the plurality of expandable polymeric microspheres, under processing conditions, including temperature and shear rate, selected to form an expandable extrudable composition; (C) extruding the expandable extrudable composition through a die to form the polymer foam; and (d) at least partially expanding a plurality of the expandable polymeric microspheres before the expandable extrudable composition exits the die.