Polymer compositions may be converted to foam products using physical and/or chemical blowing agents. Foam products include, for example, extruded thermoplastic polymer foam, extruded polymer strand foam, expandable thermoplastic foam beads, expanded thermoplastic foam beads or expanded and fused thermoplastic foam beads, and various types of crosslinked foams.
The foam products may take any known physical configuration, such as sheet, round, strand geometry, rod, film, solid plank, laminated plank, coalesced strand plank, profiles and bun stock. Foam densities range from about 5 to 800 kilograms per cubic meter and cell size ranges from less than about 0.05 mm to about 15 mm. Open cell content can vary from 0 to 100 volume percent, depending upon component selection and type of process.
Foams optionally employ a stability control agent (such as glycerol monostearate) and are optionally perforated to enhance or accelerate gaseous permeation exchange wherein blowing agent exits from the foam and air enters into the foam. Various other additives (such as nucleating agents, antioxidants, pigments, fire-retardants) may optionally be incorporated into the foamable compositions.