In this research, tensile and fracture behavior of polypropylene (PP) toughened with two types of thermoplastic polyolefin elastomers (TPOs) and filled with fumed silica are investigated. The TPOs are both propylene- and ethylene-based thermoplastic elastomers. Three percentages of TPO (0, 10, and 20 wt%) and four percentages of fumed silica (0, 1, 3, and 5 wt.%) are used. The addition of ethylene-based TPO to PP show higher values of modulus and tensile strength than propylene-based TPO. In contrast, propylene-based TPO show higher elongation at break which by increasing this type of TPO the elongation at break increase by 788%. The presence of fumed silica in the PP/TPOs blend improve the tensile strength and modulus but declined the elongation at break. Fracture behavior analysis of these compounds is performed by utilizing the essential work of fracture (EWF) approach. The outcomes demonstrate that both types of TPO in PP cause cavitation and fibrillar structures that increased the elastic and plastic work of fracture. Adding 10 wt.% ethylene- and propylene-based TPO to PP, the values of w e and βw p increase by 63%, 100% and 124%, 123%, respectively. Morphological observations show that fumed silica is located mainly around TPOs particles or at the PP/TPOs interfaces. The addition of fumed silica also reduce the size of the pores, which indicate a slight reduction in the amount of plastic work. However, fumed silica with low percentages increase the amount of elastic work and then reduce it. Also, the compound with 10 wt.% propylene-based thermoplastic elastomers and 1 wt.% fumed silica had the best toughness-stiffness-strength balance among the samples based on the optimization results.
Thermoplastic elastomeric nanocomposites have a wide range of applications in the automotive, medical, electronics, and energy sectors. Good mechanical and fracture performances are typically needed to reach the desired properties for the applications. In this study, tensile and fracture properties of exfoliated graphite (EG) filled PP toughened with ethylene-vinyl acetate (EVA) are examined. Accordingly, four levels of EVA (0, 10, 20, and 30 wt.%) and EG (0, 1, 3, and 5 wt.%) are utilized. The full factorial design is employed to explain the effect of independent parameters and their interaction on responses. The essential work of fracture (EWF) methodology is also employed to investigate the fracture behavior of the blend nanocomposites. By increasing EVA, the elongation at break and non-EWF are increased by 188% and 75%, in succession. Moreover, the tensile modulus is improved up to 11% by increasing EG. The compound with 10 wt.% EVA and 1 wt.% EG has the best toughness-strength-stiffness balance based on the optimization results.
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