Ref.: MpoErec09-001
Apresentador: Michelle Sostag Meruvia
Autores (Instituição): Meruvia, M.S.(Pontifícia Universidade Católica do Paraná); Neto, N.C.(Pontifícia Universidade Católica do Paraná);
Resumo:
In selective laser sintering a powder material, mostly polyamide 12 (PA12), is fused by a CO2 laser following the cross-sectional profile of a digital model, originating a solid 3D object. The temperature on processing can reach values as high as 170 oC, resulting in polymer molecule’s chemical structure changes due to loss of molar mass and C-N bonds breakage. The heat induced degradation, in turn, result in loss of mechanical properties and surface finishing in final objects. Therefore, the recommendation is to limit the re-use of sintered materials to small amounts mixed with new material in further processes. Consequently, a large amount of non-sintered material is wasted, leading to increase in production costs. In this study, nanocomposites of selective laser sintered PA12 (s-PA12) as the polymer matrix and graphene oxide GO at different loads (1.0, 2.5 and 5.0 wt.%) as fillers, were produced. Graphene oxide, with properties such as high electrical and thermal conductivity, were used aiming at the improvement in mechanical and electrical properties of s-PA12. For that, the s-PA12 powder was mixed under magnetic stirring with GO dispersed ultrasonically in formic acid, which led to a higher dispersion of GO in the polymeric matrix. The resulting powder was characterized by X-ray diffractometry (XRD), infrared spectroscopy (FTIR), differential thermal analysis (DTA) and scanning electronic microscopy (SEM) and its properties were compared to the original powder. Powder material analysis shows that the acid mixing process does not affect the powder morphology nor its physicochemical properties. The highest improvement in mechanical properties was observed for the s-PA12/GO thermally sintered nanocomposites at 5.0 wt.% filler loading, for which an average Shore D hardness was measured to be about ~ 15% higher than the hardness measured for the samples without GO addition, but almost the same as the value of given in the literature for the non-processed (virgin) powder, while an increase of ~ 40% in the Young’s modulus was observed.