Mechanical behavior and essential work of fracture of surface‐modified exfoliated graphite filled polypropylene/ethylene‐vinyl acetate blend nano‐composites

Abstract

Polymer nano-composites have an extensive diversity of applications in many areas, including automotive, construction, healthcare, and electronics. Excellent tensile and fracture properties are commonly required to achieve the appropriate properties. In this research, the tensile and fracture behavior of polypropylene (PP)/ethylene-vinyl acetate (EVA)/exfoliated graphite (EG) blend nanocomposites are investigated. The exfoliated graphite was either unmodified or surface-modified with ammonium polyphosphate (APP). When the modified exfoliated graphite (EG-g-APP) was added to PP/EVA compounds, the tensile properties were more enhanced compared to unmodified EG. The elongation at break was around 2 times greater in the blend containing EG-g-APP. The essential work of fracture (EWF) approach was utilized to evaluate the effect of EG and EG-g-APP on the fracture behavior of PP/EVA blends. The w e and βw p values of the nano-composites including EG-g-APP were mainly higher than nano-composites containing EG at the same nano-filler concentration. Also, according to SEM imaging, the EWF analysis results suggested that the preeminent mechanism of fracture in various compounds is the debonding of EVA from PP, which causes shear yielding and fibrillar structures on the surface of the compounds. It was observed that as EVA increased, the number of cavities and the size of fibrillar structures were increased. Enhancement in fracture toughness and matrix resistance was attributed to a growth in the number of nano-voids and a decrease in voids' size.ammonium polyphosphate, essential work of fracture, ethylene-vinyl acetate, exfoliated graphite, polypropylene, tensile properties | INTRODUCTIONPolypropylene (PP) is the commonly used polyolefin in many applications such as interior construction, food packaging, agriculture, textiles, the automobile industry, electronics appliances, chemical preservation, and so forth. due to its good chemical resistance, easy processing, high thermal stability, and low cost. Against these appropriate properties, the sensitivity to notch and the low toughness of this polymer, especially at low temperatures

Fracture toughness of PA6/POE‐g‐MA/TiO2 ternary nanocomposites according to the essential work fracture method

“…Also, to establish the condition of self‐similarity, the values of displacement must increase by increasing the length of the ligament. [ 36,37 ]…”

“…The approaches related to this solution are classified as linear elastic fracture mechanics (LEFM), elastoplastic fracture mechanics, and post‐yielded fracture mechanics (PYFM). [ 36,37 ]…”

“…The approaches related to this solution are classified as linear elastic fracture mechanics (LEFM), elastoplastic fracture mechanics, and post-yielded fracture mechanics (PYFM). [36,37] On the basis of the theory of LEFM, the fracture toughness of brittle materials is commonly defined. These materials usually fail after reaching the maximum load (stress) with catastrophic crack growth.…”

“…The linear elastic fracture mechanics method is commonly employed for brittle materials but is not always applicable to ductile materials due to the importance of the plastic deformation zone, which is inconsistent with the linear elastic fracture mechanics assumption. [36,37] Other procedures based on non-linear fracture mechanics (PYFM) have been developed to overcome this problem.…”

“…The J-integral and the essential work of fracture (EWF) methods, which are based on post-yielded fracture mechanics, are typically used to evaluate the toughness of ductile polymers. [37,38] In comparison to the J-integral procedure, the EWF method has several advantages, including the ability to evaluate the toughness of thin materials, the simplicity and speed of test execution, and the capability to track crack growth and fracture behavior (i.e., both at crack initiation and crack propagation). [39] There are several studies using EWF, to study the fracture characteristic of polymer nanocomposites based on polyamide/POE-g-MA.…”