Mechanical Behavior and Fracture Toughness Evaluation of Multiphase Polymer Nanocomposites Using Impact and J-Integral via Locus Method

Abstract

Fracture behaviors of fibrillar silicate clay (MMT) filled thermoplastic polyolefin (TPO) containing polypropylene (PP) blended with ethylene-propylene-diene monomer (EPDM) were systematically investigated using impact test method and J-integral by locus method. Drastic increase in impact strength is observed for all developed compositions and generally shows higher value for the selected phases containing dispersed nanoclay in PP matrix. A fracture mechanics approach has been adopted by mode I test, and the effects of specimen geometry have been investigated. Increase in interlaminar fracture energy value, Gc, and J-integral value, Jc, is marked as the crack propagated through the composite; that is, a rising “R-curve” is observed. Toughness measurements revealed that the fracture toughness increased with increasing clay content reaching maximum at 3 wt% of clay than pure PP. Moreover, enhancement of fracture toughness was more remarkable than that of stiffness. The fracture surfaces taken from different specimens were observed for exploring the fracture mechanisms using transmission electron microscopy (TEM) revealed a strong particle-matrix adhesion.