Prediction, evaluation and mechanism governing interphase strength in tensile fractured PA-6/MWCNT nanocomposites

Abstract Present investigation focuses on exploring the tensile fracture mechanism in Polyamide-6 (PA-6) reinforced with low contents of Multi-walled Carbon nanotubes (MWCNTs). Fractography revealed not only uniform dispersion of MWCNTs but also appreciable interfacial interaction between PA-6 matrix and MWCNTs. Polymer sheathing and formation of bead-like morphology on fractured MWCNTs also confirmed strong interfacial adhesion. Upon fracture, the MWCNTs bridged over broken polymer facets and contributed towards improvement in strength of the composites by stress transfer effect. The bonding of MWCNTs on favourable sites along PA-6 chain was observed from FTIR, while the formation of strong interphase was confirmed by theoretical modelling of interphase strength and the thickness of interphase layer by using modified combination model of Leidnar-Woodhams model and Pukanszky model for cylindrical nanofillers . Mechanism for the formation of a strong and dense interphase and its contribution for improved tensile properties of PA-6/MWCNT nanocomposites are also explained herein.