Mechanical properties of linear low-density polyethylene (LLDPE)/clay nanocomposites: Estimation of aspect ratio and interfacial strength by composite models

Abstract

In this study, mechanical properties of the linear low-density polyethylene (LLDPE)/org-clay nanocomposites prepared by melt processing were investigated. Aspect ratio (A(f)) of the clay layers were estimated by using the Halpin-Tsai (H-T) micromechanical model based on the enhancement of the Young's modulus (E) with the clay loading (phi). Strength of interfacial interactions (tau and B parameters) between the clay layers and polymer chains were also quantified by two indirect modeling approaches based on the improvement in tensile strength (or yield stress) of the nanocomposite samples. Interfacial strength parameters, tau and B, were found as about 5MPa and 17.3, respectively. The average value of A(f) was calculated as similar to 35 by the H-T model. In the TEM study, it was observed that the nanocomposite samples showed mixed morphology that could be defined as some exfoliated layers, intercalated clay stacks, and two to three layered tactoids present together within the samples. An estimated A(f) value was also confirmed by the TEM study. On the other hand, it was also shown that the A(f) value is consistent with previously reported values calculated by the modeling of melt rheological data of samples obtained from dynamic oscillatory shear measurements.