Theoretical models for prediction of mechanical behaviour of the PP/EPDM nanocomposites fabricated by friction stir process

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In this study, thermoplastic polyolefin elastomeric (TPO) nanocomposites were fabricated by friction stir processing. The effect of different pin geometries on clay dispersion and mechanical properties of the TPO nanocomposite reinforced with 3% wt nanoclay has been first investigated. The optimum pin geometry namely threaded cylindrical pin was then used to fabricate the nanocomposites containing 3, 5 and 7 wt% nanoclay. The results showed that increase in the clay content increased the tensile strength and tensile modulus of the nanocomposite from 15.8 to 22.76 MPa and 568 to 751 MPa, respectively. The experimental stress – strain curves of nanocomposites were compared with eight constitutive models including Mooney – Rivlin, the second-order polynomial, Neo – Hookean, Yeoh, Arruda – Boyce, Van der Waals and the third- and sixth-order Ogden. The comparisons showed that there was an agreement between the experimental data and the sixth-order Ogden model. Three micromechanical models Halpin – Tsai, inverse rule of mixture and linear rule of mixture were applied to investigate the Young’s modulus of nanocomposites. Because of the significant difference between the Young’s modulus obtained from these models and the ones obtained from experimental data, a modifying factor was used to improve the theoretical predictions obtained from the models.