%0 Journal Article
%T Mechanical Behavior and Fracture Toughness Evaluation of Multiphase Polymer Nanocomposites Using Impact and -Integral via Locus Method
%A Bishnu P. Panda
%A Smita Mohanty
%A S. K. Nayak
%J Chinese Journal of Engineering
%D 2013
%R 10.1155/2013/245718
%X 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 -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, , and -integral value, , is marked as the crack propagated through the composite; that is, a rising ¡° -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. 1. Introduction Polypropylene (PP) offers a very attractive combination of physical and mechanical properties at a relatively low cost, which makes it a versatile material with continuously increasing applications. However, not all the characteristics of this material are suitable for common service conditions. For instance, PP exhibits poor low-temperature impact resistance because of its low temperature and high crystallinity. In order to overcome these limitations, elastomers such as ethylene-propylene random copolymer (EPR) [1], ethylene-propylene-diene terpolymer (EPDM) [2], and poly(ethylene-co-1-octene) [3] among others [4, 5] have been added to PP, as impact modifiers. Further, due to incompatibility of PP with these elastomers, functionalized polymers have been used as blend compatibilizers to improve interfacial adhesion. Layered silicate clays are also used as fillers in polymers which have gained considerable attention due to the ability to achieve exceptional property enhancements at very low level loading. Layered silicate clays such as montmorillonite (MMT) have attracted much attention because of their unique properties, such as large aspect ratio, high surface area, and low cost. Addition of low level loading of these silicate clays to polymers markedly improves their tensile strength, stiffness, and heat resistance and facilitates processing thus reducing component weight. However, in order
%U http://www.hindawi.com/journals/cje/2013/245718/