Effect of annealing on the mechanical properties of composites of PLA mixed with Mg and with HA

Polylactic acid (PLA) is a bioresorbable and biocompatible material and is a promising alternative to the current materials used for permanent implants as it has osteosynthesis properties. However, this material has some drawbacks due to its low mechanical and thermal resistance after 3D printing. Extensive research has been conducted to improve the properties of this material, for example, with the addition of other compounds, such as magnesium (Mg) or Hydroxyapatite (HA). These reinforced materials have been shown to reduce the internal stress of the matrix of PLA, improving the thermal, optical and structural properties of the material, even though the performance achieved is lower than needed to be implanted. In addition, although it is known that the addition of Mg or HA affects the mechanical performance of the material, mechanical properties have not been studied in the literature. Thus, the aim of this study is to research the effect of thermal post-processing based on annealing of composites made of PLA with Mg and PLA with HA, manufactured by fused filament fabrication, with the goal of finding an improvement in the mechanical properties of these materials. As a result, different designs of annealing processes have been studied with different reinforced materials and their mechanical properties have been compared, studying axial traction and compression, radial compression as well as flexibility, among others. The comparative results achieved show the relevance of the design of the annealing process for the improvement of the mechanical properties of these materials.