SH-SSQ as a modifier for superior mechanical properties and improved plasticity of 3D printed PLA

This work confirms that the use of silisequioxanes in the modification of polymeric and composite materials to change their properties is possible in the range of low modifier concentrations, not exceeding 2.5%. This study investigates the impact of (3-thiopropyl)polysilsesquioxane (SSQ-SH) on the properties of polylactide (PLA) for 3D printing. Microscopic analysis using SEM and EDS mapping proved that SSQ-SH is well dispersed in the polymer matrix in the concentration range of 0.25-2.5 wt%, agglomerations were observed at 5 wt% concentration, which reduces the homogeneity of the material and is also reflected in the mechanical test results. Mechanical testing shows SSQ-SH enhances flexibility and toughness, with the most significant improvements observed at 1 wt% and 1.5 wt% concentrations. Specifically, elongation at break increases by up to 56% and impact strength by up to 37% compared to unmodified PLA. These results suggest SSQ-SH is an effective plasticizer, improving interlayer adhesion and reducing brittleness. The optimal SSQ-SH concentrations for maximizing mechanical performance and material integrity are 1 wt% and 1.5 wt%. Part of the produced samples was conditioned in a climatic chamber, it was observed based on DSC and XRD analysis that the crystallinity of the materials significantly increases after exposure to UV radiation, which is also confirmed by microscopic observations. This study highlights the potential of SSQ-SH in improving the performance of 3D printed PLA materials and efficient modification is possible even in the range of low modifier concentrations, not exceeding 2.5%.