The additive manufacturing of natural fibre-reinforced polymers is a pivotal method in developing sustainable engineering solutions. Using the fused filament fabrication method, the current study investigates the additive manufacturing of hemp-reinforced polybutylene succinate (PBS) alongside its mechanical characterization. Two types of hemp reinforcement are considered: short fibres (max. length smaller than 2 mm) and long fibres (max. length smaller than 10 mm), which are compared against non-reinforced (pure) PBS. A detailed analysis is performed regarding the determination of suitable 3D printing parameters (overlap, temperature, nozzle diameter). In a comprehensive experimental study, additionally to general analyses regarding the influence of hemp reinforcement on the mechanical behaviour, the effect of printing parameters is determined and discussed. Introducing an overlap in the additive manufacturing of the specimens results in improved mechanical performance. The study highlights that the Young’s modulus of PBS can be improved by 63% by introducing hemp fibres in conjunction with overlap. In contrast, hemp fibre reinforcement reduces the tensile strength of PBS, while this effect is less pronounced considering overlap in the additive manufacturing process.

Aligned with the Sustainability Development Goals (SDGs), we present the complete methodology of preparing bio-based polymer filaments to be used in additive manufacturing, specifically by means of so-called Fused Filament Fabrication (FFF) in 3D printing. Filament production and 3D printing were both developed and optimised in this work. First, we focused on the steps of producing and optimising the extrusion process of unreinforced polylactic acid (PLA) composite filaments. Second, we studied the resulting material properties by discussing the selection of a specimen geometry and the international standards adequate for FFF 3D printing. Moreover, we investigated the process parameters in order to achieve reliable structures. Based on the reinforcement material (stereocomplex fibres (Sc-PLA fibre) and bi-component fibres (bi-co PLA fibre), base-matrices were selected for producing un-reinforced filaments. In this way, we present the complete preparation approach by identifying problems and pitfalls for fostering studies of bio-based polymer filaments.

Shape memory polymers (SMPs), a class of polymers exhibiting the unique ability to restore deformation induced during the programming process in response to external stimuli, have garnered significant attention. In this study, our objectives were two-fold: to develop an efficient device for programming SMP hinges crafted from polyetheretherketon (PEEK) and to optimize their performance for potential utilization in space applications. Two versions of the programming device were constructed and compared. Through three systematic experiments, we identified optimal programming and recovery conditions for the hinges, revealing the best shape memory effects (SMEs) at a programming temperature of $250 °\mathrm{C}$. Remarkably, the hinges were able to recover the previously induced deformation up to 100%, maintaining functionality down to a lower temperature limit of $150 °\mathrm{C}$. Notably, these hinges demonstrated a wide operational range of over $180°$, rendering them promising for space applications, as extensively discussed within the manuscript. However, challenges arise due to the high recovery temperature of $150 °\mathrm{C}$, presenting obstacles in achieving optimal functionality in the demanding conditions of a space environment.