Characterizing the influence of Temperature on the short-term mechanical properties of 3D printed PLA.

Abstract

This thesis investigates the influence of temperature on the mechanical properties of Polylactic Acid (PLA) manufactured using 3D printing, with a particular focus on tensile modulus and yield strength. The study adheres to the ISO 527 2/1B standard for developing tensile specimens, which were fabricated using a Creality Ender-3 Pro 3D printer employing Fused Deposition Modelling (FDM) technology. Specimens were printed with alternating orientations of (0°, 90°) and (45°, -45°) and at three different infill densities: 50%, 75%, and 100%. The mechanical properties were evaluated at four distinct temperatures: 20°C, 35°C, 40°C, and 50°C. The results demonstrated a clear trend of decreasing tensile modulus and yield strength with increasing temperature. As the temperature rose, the specimens became softer and lost both strength and stiffness. There are various limitations associated with using above glass transition temperature (≈60°C). In this case, PLA undergoes a transition to a more flexible state, which decreases its mechanical strength and makes it less indicative of normal usage conditions. This results in imprecise evaluations of its effectiveness. Additionally, a comparative analysis revealed that the (0°, 90°) infill orientation generally provided better load distribution and resistance than the (45°, -45°) infill orientation. This means that applied forces were more equally distributed and handled throughout the structure, leading to greater resistance to deformation. Higher tensile modulus and yield strength at elevated temperatures were the result of this effective load control, which improved the material’s overall performance and resilience under stress. Finally, the mechanical constants were evaluated from modulus vs temperature & yield strength vs temperature graph. This study offers valuable insights for enhancing the design and application of PLA in environments subjected to varying thermal conditions, thereby improving reliability and performance. Future research may expand the range of temperature variations and investigate additional mechanical properties to achieve a more comprehensive understanding of PLA's behaviour under different conditions.