Studying the influence of friction stir welding parameters on the mechanical properties of PP/EPDM/Clay nanocomposites by response surface methodology combined with desirability function approach

Abstract

The main objective of the present study is to investigate the influence of friction stir welding (FSW) parameters using a novel tool on the mechanical properties of polypropylene-ethylene-propylene diene monomer/clay (PP/EPDM/Clay) nanocomposite. The response surface method of design of experiments in combination with the desirability function approach is applied to quantify the effects of clay content, tool rotational speed, welding speed, and tool shoulder temperature on tensile strength and elongation of welded joints. It was observed that the tool rotational speed had the maximum effect on the tensile strength, while the greatest influence on the elongation was due to the tool shoulder temperature. The addition of clay nanoparticles up to 6 wt% into the PP matrix reduced the tensile strength and elongation of the weld by about 38% and 20%, respectively. Moreover, an improvement of about 45% was observed in the tensile strength when the rotational speed increased from 800 to 1600 r/min, while the tensile strength deteriorated by about 29% when the linear speed increased from 10 to 20 mm/s. A rise in shoulder temperature from 50 to 100°C was also accompanied by an enhancement in the tensile strength and elongation by 20 and 50%, respectively. Nevertheless, the desired operating conditions were found to be 0.85 wt% for clay, 1390 r/min for the tool rotational speed, 10 mm/min for the welding speed, and 100°C for the tool shoulder temperature. The fracture morphologies obtained by scanning electron microscopy (SEM) were in good agreement with corresponding tensile strength and elongation results.