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
In this article, the 3D printed polyamide12/carbon nanotube (PA12/CNT) nanocomposites were joined using laser welding. The factorial design method was applied to study the effect of laser power, welding velocity, and CNT content on the tensile and impact strengths of welded samples. The differential scanning calorimetry and thermogravimetric analysis were also used to measure the thermal stability and weight loss temperature of the nanocomposite. The results indicated that the increase of CNTs enhanced the thermal stability of the nanocomposite and so increased its melting point and crystallinity percentage. The impact and tensile strengths of the weld enhanced when laser power elevated from 40 to 50 W, but elevation of laser power up to 60 W decreased the impact and tensile strengths due to thermal degradation of the nanocomposite. A rise in welding velocity from 10 to 20 mm/s enhanced the tensile strength, while the impact strength initially enhanced and then decreased. The highest tensile strength obtained at 2 wt% CNT, whereas the addition of CNTs up to 4 wt% led to their agglomeration, which resulted in the reduction of impact and tensile strengths. Finally, the optimal conditions for concurrent increase of impact and tensile strengths include the laser power of 51 W, welding velocity of 12.5 mm/s, and CNT content of 2.3 wt%.
Polymer nanocomposites find diverse applications in the aerospace, automobile and electronic industries due to good corrosion resistance, high specific strength and excellent processing ability. However, the production of complex and larger parts typically requires welding technology. In this research, fused filament fabrication technique was used to prepare polypropylene nanocomposite reinforced with graphene nanoplates. The polypropylene/graphene nanocomposites were then joined using the friction stir welding. Afterward, different analyses such as thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, tensile testing and hardness testing were applied to examine the effects of the process parameters on the microstructure and mechanical properties of the nanocomposite. The results of thermal analysis indicated that the addition of graphene nanoplates improved the melting point and crystallinity percentage of the polypropylene nanocomposite. Mechanical characterization of the welded samples indicated that the increase of rotational speed from 500 to 750 rpm enhanced the tensile strength of weld joint, while it reduced the hardness. Moreover, an increase in the welding speed from 10 to 30 mm/min resulted in a reduction in the tensile strength and an improvement in the hardness. The highest tensile strength of the weld was obtained by addition of 1 wt% graphene to polypropylene, whereas the hardness of the weld was maximized by addition of 2 wt% graphene. Nevertheless, the desirable combination of the process parameters for simultaneous enhancement of tensile strength and hardness was achieved by rotational speed of 667 rpm, welding speed of 16 mm/min and graphene content of 1.5 wt%.
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