A comparison of granule-based material extrusion and fused filament fabrication in the performances of TPS/PBS blend

Fused filament fabrication (FFF) has been widely adopted across numerous sectors, with its performance closely linked to the quality of the filaments employed. This study explores the characteristics and applicability of a self-fabricated, bio-based thermoplastic starch (TPS)–polybutylene succinate (PBS) filament in FFF processing. A comparative evaluation was conducted between the filament and its corresponding preformed pellets, assessing properties such as density, melt flow index (MFI), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and rheological behavior. Furthermore, the pellets were utilized directly in granule-based material extrusion (GME) 3D printing to fabricate tensile test specimens, which were benchmarked against those produced via FFF. The results revealed that FFF-processed material exhibited a higher MFI but lower stiffness, glass transition temperature (T_g), cold crystallization temperature (T_cc), and melting temperature (T_m) relative to the GME-processed counterpart. These differences are attributed to chain scission and thermal degradation occurring during filament extrusion. Mechanical testing demonstrated superior tensile strength (30.36 MPa) and Young's modulus (478.88 MPa) in GME specimens compared to those from FFF (28.24 MPa and 426.43 MPa, respectively). Nonetheless, computed tomography (CT) and scanning electron microscopy (SEM) analyses indicated greater structural consistency in FFF samples, characterized by reduced void content and a more uniform layer architecture—reflected in the lower standard deviation of tensile strength. Although the filament exhibits comparatively diminished material properties, its superior printability in the FFF process underscores its viability for future applications. Overall, this highlights the necessity to enhance the printability of GME technique in purpose of a greater precision in the fabricated specimens.