MWCNT-driven modulation of thermal and flow properties in PTT/PP polymer systems

The thermal and viscoelastic performance of polymer blends is decisive for their deployment in advanced engineering and electronic applications. Here, we report a systematic investigation of immiscible poly(trimethylene terephthalate) (PTT)/polypropylene (PP) blends reinforced with multiwalled carbon nanotubes (MWCNTs). While the incorporation of MWCNTs did not markedly alter the thermal degradation profiles, it significantly modified the viscoelastic behavior by inducing a constrained polymer region within the PTT phase. Quantitative analysis of filler dispersion effectiveness, entanglement density, reinforcing efficiency, and constrained volume provides new insights into nanotube–matrix interactions. Rheological results revealed a terminal-to-nonterminal transition with increasing nanotube content, confirming percolated network formation at low filler loadings. These findings establish clear structure–property correlations that extend beyond qualitative descriptions, offering a predictive framework for tailoring immiscible blends through nanofiller engineering. Such insights highlight the potential of PTT/PP/MWCNT systems in functional applications, including lightweight structural components and conductive composites for electronics.