Mechanical properties and degradation of laser sintered structures of PLA microspheres obtained by dual beam laser sintering method

Abstract

AbstractThis paper discusses the influence of process parameters on the degradation and the mechanical properties of laser-sintered polylactide (PLA) microspheres obtained using the novel dual beam laser sintering method (DBLS). DBLS is a technique developed by our team that is a modification of standard polymer laser sintering (pLS), with the potential to reduce polymer degradation during the process. The PLA microspheres were produced using the standard emulsion-solvent evaporation method. The laser sintering process was carried out in a wide range of process parameters to obtain samples with various degrees of sintering. Next a number of tests were conducted to assess the physicochemical properties of these samples, including visualization techniques (SEM, digital microscopy and photography), gel permeation chromatogrphy (GPC), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis (DMTA) and static compression tests. The work shows that for different sets of process parameters, it is possible to obtain a product with similar mechanical properties, but at the same time with a completely different degree of polymer degradation. Hence, the hypothesis that when assessing the sinter quality one should take into account not only the mechanical properties of the detail, but also the degree of polymer degradation, which is of great importance, for example, in biomedical applications. It has also been shown that the DBLS method has a potential to reduce the degree of degradation of the sintered polymers and the post-process material outside the sintering zone.