In this article, response surface methodology (RSM) has been applied to simultaneously optimize the tensile and impact strength of polypropylene (PP)/nitrile butadiene rubber (NBR)/halloysite nanotubes (HNTs)/maleic anhydride (MA)‐grafted‐PP nanocomposites. Three levels of material parameters, including NBR (10, 20, and 30 wt%), HNTs (1, 3, and 5 wt%), and PP‐g‐MA (3, 9, and 15 wt%) as compatibilizers were used to design the experiments according to Box‐Behnken design. In order to investigate the morphology of nanocomposite samples, a scanning electron microscope was used. The model predicted that both the tensile strength and impact strength of nanocomposite were peaked between middle and high levels of HNTs content. There was also a peak for NBR loading in the main effect plot of impact strength. Two‐way interactions of all parameters were significantly affecting both responses. Based on RSM models using the desirability function, the optimum values of input parameters leading to optimized tensile strength and impact strength were predicted to be 17.87, 4.35, and 15 wt% for NBR, HNT, and PP‐g‐MA, respectively. Confirmation experiments were in good agreement with the predicted values.

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In this paper, PP/EPDM nanocomposites with 5 wt% nanoclay are fabricated by friction stir processing (FSP) and compared to the results obtained via a conventional twin screw extruder (TSE). Also, the effects of process parameters of these process on morphology and mechanical properties of this nanocomposites are investigated using Taguchi analysis. The prepared PP/EPDM/clay nanocomposites by two methods were characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and mechanical property tests. Comparison of the results of these methods indicated that PP/EPDM/clay nanocomposite fabricated by FSP had a better dispersion of nanoclay and mechanical properties. The results show that by addition of 5 wt% nanoclay to the base material, the tensile strength and tensile modulus of FSP sample are 12% and 8% higher than the TSE sample. The TGA results shows that, the temperature at 50% weight loss for PP/EPDM blend is 382°C. While this temperature for TSE and FSP samples are 395°C and 406°C, respectively. Under optimal conditions of rotational speed of 1,200 rpm, traverse speed of 50 mm/min, shoulder temperature of 100°C and number passes of 3, simultaneous maximization of tensile strength (19.35 MPa), tensile modulus (643 MPa), impact strength (63 J/m) and elongation at break (101%) can be obtained. POLYM. COMPOS., 40:3306–3314, 2019. © 2018 Society of Plastics Engineers