Microstructural correlations to micromechanical properties of polyamide-6/low density polyethylene-grafted-maleic anhydride/nanoclay ternary nanocomposites

Abstract

Ternary nanocomposites were fabricated based on an optimized impact modified polyamide-6 (PA-6)/low density polyethylene grafted maleic anhydride (LDPE-g-MA) blend composition with varied concentration (∼0–6 wt.%) of organoclay, Cloisite 30B™. The microstructural attributes such as state of intercalation/exfoliation/crystalline organization and fractured surface topography of the nanocomposites by using electron microscopic and X-ray diffraction techniques. The X-ray diffraction studies have revealed that the crystallinity of the nanocomposites remained inappreciably affected. Dynamic mechanical analysis revealed an increase in T g of the nanocomposites relative to the neat PA-6 and the optimized PA-6/LDPE-g-MA blend matrix indicating the reinforcement effects/mechanical restrictions imposed by the nanoclay layers to the polymer chain mobility. The quasi-static mechanical response and micromechanics aspects concerning interfacial effects and stress-transfer efficiency of the nanocomposites using Halpin-Tsai, Hui-Shia, Takayanagi and Pukanszky models have been investigated. Micromechanical analysis based on minimalistic assumptions revealed interphase-thickness reduction at higher nanoclay content with a correspondence to the reduction in reinforcement-efficiency. Scanning electron microscopy of the cryo-fractured xylene-etched nanocomposite surfaces have indicated a nanoclay content dependent transition from homogeneous to inhomogeneous deformation assisted by the formation of random microfibril-like interconnected networks.