Importance

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Abstract

The invention describes a process for the preparation of a natural fiber and thermoplastic composite and the resulting products therefrom. The process includes the steps of mixing the natural fiber and the thermoplastic in a blender with a porosity aid and an interfacial agent to form a mixture; adding the mixture to a heated extruder; compressing the mixture with an extruder screw having a plurality of flight sections, at least one of the flight sections serving as a compression flight section which compresses the mixture by having its flights spaced closer together than other adjacent flight sections, and at least one other vent flight section which allows gaseous reaction products to be removed from the extruder through a vent in the extruder by having its flights spaced farther apart than the compression section, the vent flight section being positioned after the compression flight section; extruding the mixture through an extrusion die as a composite; and shaping the composite in a vacuum calibration device to a desired profile. The process further includes the step of co-extruding a second thermoplastic onto the natural fiber/thermoplastic composite for some applications (e.g., windows, doors and siding).

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First Claim