Abstract:
Methods for forming foamed polyurethane composite materials in an extruder including a vacuum section are described. One method includes introducing a polyol, a di- or poly-isocyanate, and an inorganic filler to a first section of an extruder and mixing the components. After mixing, the composite material is advanced to a second section of the extruder, which is maintained at a vacuum pressure. The composite material can begin foaming in the second section and then be extruded from the output end of the extruder. The vacuum pressure of the second section removes non-foaming related gasses entrained in the composite material. A further method includes directing the extruded composite material into a mold.
Abstract:
Methods for forming composite materials containing fiber in an extruder are described. A first method includes introducing a polymeric material, an inorganic filler, and a fiber to an extruder. A fiber metering device is used to control the rate the fiber is introduced to the extruder based on the extrusion rate of the extruder. A further method is described that includes introducing a polymeric material and an inorganic filler to an extruder. Then, downstream of the polymeric material and inorganic filler, a fiber metering device introduces a constant weight percentage of fiber to the extruder based on the amount of polymeric material and inorganic filler introduced to the extruder. After the polymeric material, inorganic filler, and fiber are introduced to the extruder by either method, the components are mixed to produce a composite material.