Processing and Characterization of Unidirectional Glass Fiber-Reinforced Composites from Bio-Based Polybutylene Succinate

Within this study, the processing behavior, resulting morphology, and mechanical properties of unidirectional glass fiber-reinforced polybutylene succinate (PBS/GF) composites were investigated. Therefore, a commercial grade of partially bio-based PBS with a melt flow index of 22 g/10 min (190°C, 2.16 kg) was evaluated regarding the eligibility for processing of continuous unidirectional fiber-reinforced thermoplastic composites (UD tapes). The production of the PBS-based tapes was investigated by a melt impregnation process with two different widths of 50 and 100 mm for a production speed of 3 m/min. Thus, besides the processing of initial PBS tapes, the possibility for process optimization as well as the scale-up was investigated. It was found that the shear viscosity of the PBS significantly influences the impregnation process. Investigations on scale-up and optimization of processing parameters like melt throughput, fiber spreading, and die gap showed potential for improvements. As a result, a maximum fiber mass content of 64.5% could be reached, resulting in a tensile modulus of 37.0 GPa and a tensile strength of 406.4 MPa parallel to the fiber orientation for a tape width of 50 mm. This reflects a higher tensile modulus but lower tensile strength of the investigated reference based on polypropylene (PP) and could be improved by the use of an additional coupling agent. Thus, the unidirectional glass fiber-reinforced PBS tapes can be a suitable bio-based alternative for lightweight applications based on thermoplastic composites.