Three-dimensional (3D) printing has emerged as a versatile and sustainable manufacturing route for developing natural fiber–reinforced polymer composites. In this study, the objective is to enhance the mechanical performance and surface quality of 3D-printed polylactic acid (PLA) composites by incorporating powdered pineapple leaf fiber (PLF). Composite filaments were produced using a single-screw extruder and subsequently used to fabricate test specimens through fused deposition modeling. A response surface methodology based on a central composite design was employed to evaluate the influence of fiber content (SFC), infill density (SID), and printing speed (SPS) on ultimate tensile strength (UTS) and surface roughness (Ra). The developed models demonstrated strong statistical reliability, with R 2 values of 0.9823 for UTS and 0.9689 for Ra, as supported by ANOVA. Multi-response optimization yielded an overall desirability of 0.973, corresponding to 34.80 wt% SFC, 77.42% SID, and 62.89 mm/s SPS, resulting in a maximum tensile strength of 73.89 MPa and a minimum surface roughness of 3.36 µm. The optimized composite was further examined to establish the processing–structure–property relationship. Hydrogen-bonding interactions between the hydroxyl groups of poly (lactide) fibers and the carbonyl groups of poly (lactide) were detected using FTIR spectroscopy. X-ray diffraction studies showed a moderate increase in the degree of crystallinity of the composite as a result of fiber-induced nucleation. Thermal gravimetric analysis (TGA) indicated an increase in the thermal stability of the composites. Differential scanning calorimetry (DSC) showed that the thermal transitions were more uniform. The results provide evidence that optimized processing results in good bonding between the polymer and the fiber; the composites are, therefore, characterized by structural uniformity, superior thermomechanical properties, and a data-driven approach to the creation of sustainable, high-performance PLA-based biocomposite materials for use in additive manufacturing processes.
Padmanabhan et al. (Thu,) studied this question.