Abstract: A polymeric composition to be used in producing low density foam in which the polymeric composition comprises high density polyethylene, alkenyl aromatic polymer and a linear low density polyethylene. The polymeric resins may be prime virgin resin, offgrade virgin resin, recycled resin from a post industrial source, recycled resin from a post consumer source, or blends thereof Inventive compositions for producing polymeric foam are characterized by Dynamic Mechanical Spectroscopy to have a complex viscosity (?*) in the range of 6.0×104 to 2.5×105 poise and a loss tangent (tan ?) in the range of 0.7 to 2.1 at 190° C. and a power-law relation between tan ? and ?* where the exponent is within the range between ?0.70 and ?0.30 for the temperature range of 190° to 230° C.

Abstract: A polymeric composition to be used in producing foam in which the polymeric composition comprises conventional linear polypropylene, high melt strength polypropylene and a rheology modifier resin. The conventional linear polypropylene is in an amount of from about 1 to 25 weight percent of the polymeric composition. The high melt strength polypropylene is in the amount of from about 51 to 85 weight percent of the polymeric composition. The rheology modifier resin is in the amount of from 5 to about 30 weight percent of the polymeric composition. The conventional linear polypropylene may be offgrade virgin polypropylene or recycled polypropylene from post-industrial or post-consumer sources. The rheology modifier resin is a member of the group of styrene-olefin copolymers.

Abstract: A method of making a polyolefinic foam composition comprising the steps of:(a) feeding a polyolefinic polymer into an extruder;(b) adding a nucleating agent to the resin feed;(c) optionally adding a permeation modifier to the resin feed;(d) plasticating the mixture in an extruder to form a polymeric melt;(e) incorporating a blowing agent of carbon dioxide and optionally one or more members selected from the group consisting of inorganic blowing agents, organic blowing agents, and combinations thereof;(f) incorporating at least one compatibilizing agent into said foamable composition wherein said compatibilizing agent is an oxygenated hydrocarbon that decreases the minimum pressure required to prevent prefoaming while retarding the collapse of foam due to excessive blowing agent migration;(g) uniformly mixing and cooling the foamable composition to a temperature effective for the expansion of the polyolefinic foam; and(h) extruding or ejecting the foamable composition through a die to form a polyolefinic foam.