Abstract: A method of thermoforming comprising providing a continuous sheet of thermoplastic polymeric foam, transporting said sheet through an atmosphere of at least predominantly steam at a temperature of at least 215.degree. F. maintaining said sheet in said atmosphere for a time sufficient to cause a decrease in the density thereof; thereafter while under the influence of said temperature, deforming at least a portion of said sheet to a predetermined shape and while so deformed, cooling the same to cause retention of said shape and a system for carrying out said method.

Abstract: Thermoplastic foams of polystyrene, for example, are prepared with a blowing agent which is a mixture of an organic plasticizing blowing agent, such as pentane, and an atmospheric gas, such as carbon dioxide. Typically, such foams prepared with organic blowing agent alone were aged prior to thermoforming the foam into articles. Foams prepared with the mixed blowing agent of this invention exhibit the advantage of reduced atmospheric emissions on aging.

Abstract: A method for treating foamed polymer comprising exposing said polymer to an atmosphere of at least substantially carbon dioxide at a temperature sufficient to cause transpiration, absorption and/or dissolution of carbon dioxide into said polymer and decrease the density thereof on subsequent heating.

Abstract: In the process of preparing a thermoplastic resin foam the improvement comprising extruding a molten resin-blowing agent combination from a high pressure region to a lower pressure atmosphere of carbon dioxide, water vapor or mixtures thereof.

Abstract: A method and apparatus for monitoring the average cell size of a plastic foam structure continuously emerging from a production extrusion source which include means and process steps for magnifying an image of an area of a cross-section of said foam structure, developing said image and comparing the cell size of the image with a known standard and controlling production process parameters to obtain a foam structure of predetermined average cell size.

Abstract: Improved polymeric foams are obtained by the introduction of a beneficial additive to the system by dissolving said additive into a liquid foaming agent which is a solvent therefor, combining the solution with the polymer and extruding the polymer in foamed form.

Abstract: A continuous foam production system is disclosed wherein a molten thermoplastic resin is mixed with volatile blowing agent at elevated pressure to form an extrusion mass. A helical screw extruder means is adapted to extrude the molten resin with volatile blowing agent into a low pressure foaming zone to form a foam sheet, tube or other shape. An improved fluid handling system includes storage means for holding at least one of a plurality of disparate volatile liquids under pressure sufficient to maintain a normally gaseous blowing agent in liquified state and cooling means for receiving a pressurized first stream of liquified thermally-gaseous blowing agent and cooling below its autogenous temperature. A pump operatively connected between the cooling means and extruder means increases pressure of the first stream higher than the elevated pressure of the extruder, where it may be combined with a pressurized stream of second liquid blowing agent.

Abstract: A method of making polyacetylene extrudate is described involving the extrusion of a mixture of a polyacetylene and an organic solvent. The resulting extrudate can be heat treated to form carbonaceous products. The polyacetylene extrudate experiences an increase in strength to weight ratio upon heating to elevated temperatures. It is convertible to the high strength graphitized state.