Glass Fiber/Polypropylene Composites Produced by Film Extrusion for Local Reinforcements

Short glass fiber reinforced polypropylene films with different fiber content were produced by film extrusion using a coat-hanger die. Despite the elongation flow in the coat hanger die, a highly aligned fiber orientation in processing direction was observed. The typical increase of the tensile modulus with increasing fiber content was obtained whereas the tensile strength dropped down by incorporating small amounts of fibers. With 50 wt% fiber content the level of neat polymer film is reached again. The absence of a packing and consolidation step in compare to molding processes leads to a relative high surface roughness which increases the appearance of cracks in case of a load. For further improvement an additional pressure-related calendaring step is useful.