Rapid manufacturing of PA/HDPE blend specimens by selective laser sintering: Microstructural characterization

The structure and properties of parts made by selective laser sintering (SLS) depend on the process parameters and the characteristics of the powder material to be processed. The use of polymeric blends can increase the range of structures and properties of SLS parts. This study investigates the processing of blends of polyamide (PA2200) and high-density polyethylene (HDPE) by SLS using a CO2 laser. Powder properties of undiluted polymers, mixture composition, processing parameters and their influence on the microstructure of the specimens manufactured, were evaluated. PA2200 showed higher absorption of laser energy than HDPE during the sintering of blend specimens, with subsequent thermal energy transfer to the melting of the HDPE phase. The microstructures of PA2200/HDPE blend specimens were heterogeneous with co-continuous and disperse phases depending on the quantity of HDPE. The porosity and crystallinity also changed as a function of the component proportions. These results suggest that it is feasible to manufacture blend parts using SLS, with control over the structure and properties being achieved through selecting the polymer properties (laser absorption and melt flow), powder characteristics (form and size distribution) and the optimum process parameters according to the blend composition.