Tensile properties of melt intercalated polyamide 6 – Montmorillonite nanocomposites

The effects of montmorillonite (MMT) addition level on the tensile properties of PA6-MMT polymer-layered silicate nanocomposites (PLSN) were quantified using factorial experimental design (FED) to fit experimental data to a series of polynomial response-equations. Tensile behaviour, determined via FED, was related to the morphologies of the PLSN and compared to additional experimental data, determined for both a PLSN produced as a confirmation experiment and a PA6-MMT microcomposite of equivalent MMT content. In general, the PLSN displayed mechanical behaviour in keeping with their mixed exfoliated lamellae/intercalated lamellae-stack composite morphology and with the formation of a continuous phase of constrained polymer at an MMT loading of approximately 4 wt%. The data generated by the FED response-equation for tensile modulus were compared to the predictions of the Halpin–Tsai composite theory model. A modification to the Halpin–Tsai model was made in order to take account of changes in the distribution of the number (n) of lamellae in the stack particles. Using experimental data for n, the composite moduli of the PLSN were successfully modelled as summations of the contributions of each particle fraction of varying n.