Prediction of elastic properties of polylactide/halloysite composites

Halloysite nanotubes (HNTs) incorporated poly (lactic acid) (PLA) reinforced nanocomposites were prepared by solution casting method with 2.5, 5, 7.5 and 10 wt% of HNTs concentrations. The elastic modulus (E) and tensile strength (σ) of the nanocomposites increased with the addition of HNTs. For instance, σ and E increased by 67% and 58% with addition of 5 wt% of HNTs, respectively. Beyond 5 wt%, HNTs tend to aggregate within the PLA matrix, which was confirmed by the tensile fracture surfaces' micrographs (FE-SEM) of the nanocomposites. Experimentally obtained results of E were also compared with the Halpin-Tsai analytical model (H-T model) and a 3D finite element model (FEM) which consisted of randomly distributed nanotubes. E values predicted by FEM were closer to the experimental results compared to those predicted by the H-T model. In contrast to the H-T model, FEM captures the nonlinear elastic behaviour of the experimental data very well since it takes into account the stress field interference of HNTs within the matrix.