Extrusion of polyurethane composite materials

A method of forming a polymeric composite material in an extruder, the method comprising:

• introducing at least one polyol, inorganic filler, and one or more additional components to a first conveying section of the extruder, wherein the inorganic filler comprises about 60-85 weight percent of the polymeric composite material, wherein the one or more additional components is selected from the group consisting of a catalyst, a surfactant, and a blowing agent, wherein the extruder is a twin screw extruder, and wherein the first conveying section comprises one or more transfer screws;
• transferring the at least one polyol, the inorganic filler, and the one or more additional components to a first mixing section of an extruder, wherein the first mixing section comprises a lobal screw;
• mixing the at least one polyol, the inorganic filler, and the one or more additional components in the first mixing section;
• transferring the at least one polyol, the inorganic filler, and the one or more additional components to a second conveying section of the extruder, wherein the second conveying section comprises a transfer screw;
• introducing a di- or poly-isocyanate and a fibrous material to the second conveying section, wherein the ratio of the di- or poly-isocyanate to the at least one polyol is about 0.5:1 to about 1.5:1;
• transferring the at least one polyol, the inorganic filler, the one or more additional components, the di- or poly-isocyanate, and the fibrous material to a second mixing section, wherein the second mixing section comprises a reverse screw;
• mixing the mixed at least one polyol, the inorganic filler, the one or more additional components, the di- or poly-isocyanate, and the fibrous material in the second mixing section of the extruder to provide a composite mixture;
• and
• transferring the composite mixture to an output end of the extruder.