Development and Characterization of Thermomechanically Treated and Untreated Banana Rachis Fiber/PLA Composites for Material Extrusion Additive Manufacturing

In this study, a biodegradable composite based on PLA reinforced with banana rachis fiber-derived from agricultural waste and forming the structural core of banana bunches-is developed. The fibers are evaluated with and without thermomechanical processing to enhance the properties of parts produced through material extrusion additive manufacturing (MEX), a technology with a screw feeding system. A preliminary study of the additive manufacturing process is conducted to ensure adequate processability of the matrix during the process. In addition, different composite formulations (0, 5, 10 and 15 wt.% fiber) are analyzed through morphological, thermal (TGA and DSC), rheological, and mechanical characterization, complemented by SEM analysis. This comprehensive characterization revealed that the incorporation of WTP fibers served to reinforce the PLA matrix for the tensile modulus, from 2273.54 ± 123.66 MPa to 2612.51 ± 95.16 MPa with 15% of WTP fiber. A similar trend was observed for the flexural modulus, which increased from 2456 ± 61.16 MPa in the neat PLA to 3189.68 ± 52.24 MPa for the PLA-15% WTP composite. The results demonstrate the feasibility of the process and the production of parts with acceptable quality under appropriate manufacturing conditions.