Manufacturing and Analysis of Natural Fiber-Reinforced Thermoplastic Tapes Using a Novel Process Assembly

The natural fiber-reinforced thermoplastic tape was produced using a novel process assembly that involves a drawframe and a double belt press. First, the state-of-the-art film-stacking process was modified through the integration of a drawframe to supply the natural fiber preforms for reinforcement, adding thermoplastics films as matrix material and processing them to a unidirectional tape (UD tapes) using a double belt press. Based on that, a new approach was investigated using a commingled sliver containing natural reinforcing and polymer matrix fibers to manufacture UD tapes. This leads to a reduced flow path of the matrix polymer, which is a decisive parameter for production efficiency. To ensure a homogeneous distribution and alignment of the fibers after gilling, the influence of various processing parameters on one another and the resulting UD tape quality were examined. As result, a draft ratio in the range of 10 ± 2, a low linear density (here 12 ktex) and general use of many thin in contrast to fewer heavier slivers is advisable. The differences in impregnation quality and thus the mechanical performances of the UD tapes from both processes were validated using scanning electron microscopy and mechanical testing. It was found that the commingled sliver composite had 10% higher flexural modulus and 34% higher flexural strength compared to the film-stacking-based composites. In conclusion, using commingled sliver could enable the increase in productivity and fiber volume fraction compared to film-stacking-based composites.