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.

Abstract: Members either of the polyglycol family of substances, more generally, or of the polyglycol ether subset of polyether compounds, more particularly, both for their gas absorption properties and for their plasticizing effect in a polyethylenic extrudate, are combined with physical atmospheric blowing agents, such as, nitrogen, argon, carbon dioxide, water, and blends thereof, to produce uncrosslinked polyethylenic foams having densities as low as 10 kg/m.sup.3.

Abstract: Blended non-crosslinked polyolefin compositions, which is processable into a foamed product having a fine-celled structure, including a polyolefin, optionally a copolymer of an olefin and a different ethylenic monomer, and effective amount of a fatty acid compound permeability control agent, and an effective amount of a nucleating agent. A process of preparing fine-celled foam products from the blended composition, and the final fine-celled foam products.

Abstract: Members either of the polyglycol family of substances, more generally, or of the polyglycol ether subset of polyether compounds, more particularly, both for their gas absorption properties and for their plasticizing effect in a polyethylenic extrudate, are combined with physical atmospheric blowing agents, such as, nitrogen, argon, carbon dioxide, water, and blends thereof, to produce uncrosslinked polyethylenic foams having densities as low as 10 kg/m.sup.3.

Abstract: A propylene homopolymer or copolymer, or a blend thereof, possessing both sufficient strain hardening, viscoelastic behavior, and melt ductility is heated, melted, and mixed in an extruder with an organic or inorganic physical blowing agent, or a mixture of organic and inorganic physical blowing agents, and with optional compatibilizing agents, nucleating agents, stabilizers and miscellaneous additives. This mixture is pressurized and, subsequently, is cooled to an appropriate temperature at an elevated pressure, and is extruded through a die at rates in excess of 1000 kg/hr to produce an expanded and dimensionally-stable, predominately closed cell propylene polymer foam with a density of between 10 kg/m.sup.3 and 150 kg/m.sup.3, and with a thickness in excess of 1.3 cm. The resultant foamed structure is characterized by a Foamability Index of greater than 1.9 and an Ebullition Time of less than 2.0.times.10.sup.-4 seconds.

Abstract: Members either of the polyglycol family of substances, more generally, or of the polyglycol ether subset of polyether compounds, more particularly, both for their gas absorption properties and for their plasticizing effect in a polyethylenic extrudate, are combined with physical atmospheric blowing agents, such as, nitrogen, argon, carbon dioxide, water, and blends thereof, to produce uncrosslinked polyethylenic foams having densities as low as 10 kg/m.sup.3.