This review investigates recent progress in the field of PLA-based conductive composites for 3D printing. First, it introduces PLA as a biodegradable thermoplastic polymer, describing its processing and recycling methods and highlighting its environmental advantages over conventional polymers. In order to evaluate its printability, PLA is briefly compared to other commonly used thermoplastics in additive manufacturing. The review then examines the incorporation of conductive fillers such as carbon black, carbon nanotubes, graphene, and metal particles into the PLA matrix, with a particular focus on the percolation threshold and its effect on conductivity. Critical challenges such as filler dispersion, agglomeration, and conductivity anisotropy are also highlighted. Recent results are summarized to identify promising formulations that combine improved electrical performance with acceptable mechanical integrity, while also emphasizing the structural and morphological characteristics that govern these properties. Finally, potential applications in the fields of electronics, biomedicine, energy, and electromagnetic shielding are discussed. From an overall perspective, the review highlights that while PLA-based conductive composites show great potential for sustainable functional materials, further progress is needed to improve reproducibility, optimize processing parameters, and ensure reliable large-scale applications.

This paper presents a study on the tensile, fracture, damage, and reliability properties of 3D printed polylactic acid (PLA), based on a series of experiments. The study focuses on polylactic acid (PLA) samples produced using fused filament manufacturing (FFF) technology, specifically examining unidirectional print orientations of 0°, 45°, and 90°. Tensile testing demonstrated significant anisotropy in mechanical behavior, The specimens oriented at 0° exhibited the highest tensile strength, while those at 90° showed the lowest. An increase in artificial crack length (a) resulted in a progressive decrease in the mechanical properties. Weibull analysis confirmed the presence of significant anisotropic behavior in 3D-printed PLA specimens, with ultimate stress (σu0) values ranging from 39.82 MPa for the 90° orientation to 44.69 MPa for the 0° orientation, and elastic stress (σe0) values from 35.49 MPa (90°) to 39.11 MPa (0°), indicating greater strength for the 0° oriented specimens. Damage evolution analysis showed accelerated damage, with the 90° orientation demonstrating the fastest rate of damage compared to the 0° and 45° orientations. This indicates that the 90° orientation is more vulnerable to crack propagation and has diminished structural integrity under stress.