Optimizing the mechanical properties of TiO2/PA12 nano-composites fabricated by SLS 3D printing

In this paper, the selective laser sintering process was used to fabricate the TiO2/PA12 nano-composite parts by considering the parameters of laser power, scanning speed, and TiO2 content. The response surface methodology was used to improve the mechanical properties of TiO2/PA12 nano-composite parts. The fracture surface characteristics of the specimens were examined using the scanning and transmission electron microscopy. The results indicated that the increase in laser power from 10 to 15 W improved the tensile strength, modulus, and impact strength of the nano-composite parts because of the fine dispersion of TiO2 nano-particles. An increase in the scanning speed from 2000 to 3000 mm/s resulted in the reduction of tensile strength and modulus due to lower heat input and consequently incomplete densification of polyamide-12. In addition, the increase of TiO2 content up to 5 wt% can improve the tensile strength, modulus, and impact strength, but requires increasing the laser power. However, the mechanical properties of the nano-composite parts were enhanced simultaneously at laser power of 12.4 W, scanning speed of 2000 mm/s and TiO2 content of 1.9 wt%. Moreover, the addition of TiO2 up to 5 wt% showed a slight influence on thermal stability and crystallinity of the sintered specimens.