Enhancing the tensile properties of PA6/CNT nanocomposite in selective laser sintering process

Abstract The aim of present study is to enhance the tensile strength, elongation at break and tensile modulus of polyamide 6/carbon nanotube (PA6/CNT) nanocomposite prepared by selective laser sintering. For this purpose, the optimal values of laser power, scanning speed and CNT content were estimated to enhance the tensile properties of PA6/CNT nanocomposite by using the response surface methodology and desirability function. The microstructure of specimens was observed using the scanning and transmission electron microscopy. It was observed that an increase in laser power from 5 to 10 W improved the tensile strength (21%) and elongation at break (11.4%) of the nanocomposite due to uniform dispersion of CNTs, while the further increase of laser power reduced the tensile strength (5.2%), elongation at break (5.8%) and tensile modulus (5.3%) due to thermal degradation of PA6 polymer. A rise of the scanning speed from 1000 to 2000 mm/s was associated with a reduction in the tensile strength, elongation at break and tensile modulus by about 8.3%, 13% and 3.3% respectively, which was due to lower heat input and consequently incomplete densification of the nanocomposite. The addition of CNTs up to 5 wt% can enhance the tensile properties of PA6/CNT nanocomposite, but needs increasing the laser power. The best combination of tensile properties was achieved at laser power of 7.3 W, scanning speed of 1000 mm/s and CNT content of 1.8 wt%. Moreover, the addition of CNTs up to 5 wt% showed a slight influence on thermal stability and crystallinity of the sintered nanocomposite.