Quantifying morphological and mechanical properties of thermoplastics elastomers by selective localization of nanofillers with different geometries

Abstract

Potential role of nanofiller in deciding their localization in polypropylene (PP)-natural rubber (NR) blend system is evaluated using experimental techniques followed by authentication using various theoretical approaches. Thermoplastic elastomers (TPEs) of PP-NR blend-based nanocomposites with Cloisite 15A and titanium dioxide (TiO2) were prepared by melt mixing method, using Haake rheocord-90. In pre-fixed blend composition of 70-30 (PP-NR), selective localization of nanofiller was determined by transmission electron microscopy (TEM), and quantified by Harmonic mean theoretical studies. Correlation length (ξclay) and average length of the clay layers (Lclay) measured for the dispersion of nanoclay. The dispersion efficiency of Cloisite 15A and TiO2 in blend matrix were determined by X-ray diffraction (XRD) studies. Mechanical properties of blend nanocomposites were examined by varying the nanofiller loading and compared with theoretical approaches such as Kerner, Guth, Halpin-Tsai, Einstein and Quemada models. It was found that irrespective of the geometry, the fillers migrated to the PP phase leading to significant changes in morphological development (size reduction of dispersed phase) and increased mechanical properties of 70-30 (PP-NR) neat blend. Nevertheless, it is very important to mention that at higher loading the layers of Cloisite 15A are found to penetrate partially into the NR phase due to the anisotropic nature of the clay platelets.