<p>Polypropylene (PP) is a widely used thermoplastic polymer due to its low density, chemical resistance, and good processability; however, its relatively low thermal stability restricts its application in thermally demanding environments. In this study, the influence of nanoclay (NC) loading on the structural and thermal properties of polypropylene nanocomposites was systematically investigated in order to determine an optimal filler concentration. PP nanocomposites containing 2 wt% (2% by weight) and 10 wt% nanoclay were fabricated using a melt intercalation-based hot-pressing technique without the use of compatibilizers, allowing the intrinsic effect of nanoclay content to be evaluated. Structural and morphological characteristics were examined by X-ray diffraction (XRD) and atomic force microscopy (AFM), while thermal behavior was analyzed using differential thermal analysis and thermogravimetric analysis (DTA/TG). The results revealed that the incorporation of 2 wt% nanoclay led to a predominantly exfoliated morphology with uniform dispersion of silicate layers throughout the polymer matrix. This structural arrangement significantly improved thermal stability, oxidation resistance, and surface homogeneity, as evidenced by upward shifts in melting, depolymerization, and thermo-oxidative degradation temperatures, as well as an increased residual mass fraction. In contrast, increasing the nanoclay content to 10 wt% resulted in particle agglomeration, structural heterogeneity, reduced exfoliation, and deterioration of thermal performance. These findings demonstrate that excessive nanoclay loading counteracts the beneficial effects observed at lower concentrations. Overall, this study identifies 2 wt% nanoclay as an optimal loading level for enhancing the structural integrity and thermal performance of polypropylene nanocomposites, providing practical guidance for the development of high-performance PP-based materials.</p> Graphical abstract <p></p>