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

Abstract

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.

Thermoplastic foam injection moulding of sandwich structures with short fibre-reinforced skin layers

“…This improvement is caused by the orientation of the GFs in the extrusion direction, which is in the same direction as the applied tensile load. The results are comparable with the tensile result of the glass fibre–reinforced films [20]. The glass transition (T g ) of the neat PP film in the processing direction and perpendicular to the processing direction, obtained from the peak of tan δ curves, is approximately 0.8°C and 1.94°C, respectively.…”

“…It showed a slightly higher roughness than that of the width. It should be noted that this is the same tendency which was shown for the results of film roughness [20]. Therefore, it can be clarified that the dispersion of GFs in the composite films was not drastically affected during injection moulding process.…”

“…The thickness of PP-GF 30 and PP-GF 50 is 0.39 and 0.55 mm respectively. These films were produced by extrusion process with a coat–hanger die as detailed in our work [20]. The schematic sequence of film processing via extrusion compounding with a coat hanger die is depicted in Figure 1.…”

“…Therefore, extrusion technology seems to be a suitable technology for the production of short fibre-reinforced films. According to our previous study, the fibre orientation in short glass fibre–reinforced PP films produced by the film extrusion process with the coat hanger die can be oriented in the processing direction to a high degree [20]. Consequently, these films can provide a higher tensile modulus in processing direction, whereas random fibre distribution leads to quasi-isotropic mechanical properties, but on a lower level than that is common in injection moulded parts.…”

“…The blown film extrusion process is generally employed to produce small particle reinforced thermoplastic films, nanocomposite in particular [22,23]. Conversely, the film extrusion process with calendaring unit can continuously produce the short glass fibre–reinforced films which have larger reinforcement phase [20]. These films are of interest for application as the skin layers of the sandwich structures due to their continuous production and non-random fibre orientation.…”