Enhancing the thermal and crystallization properties of polypropylene through carbon nanotube integration: a comprehensive investigation

The present investigation focuses on elucidating the novel impact of both carbon nanotubes (CNTs) and multi-walled carbon nanotubes (MWCNTs) on thermal behavior and crystallization kinetics of isotactic polypropylene (PP) composites. Our primary objective is to unveil the distinctive influence of these nanotubes on PP crystallization and its thermal properties, paving the way for tailored applications in high-performance materials. Incorporating CNTs led to a noteworthy elevation in crystallization temperature without significantly altering the polymer melting point. Furthermore, our findings revealed an increased critical cooling rate in correlation with higher CNT concentrations, representing a crucial parameter for nucleation effectiveness, independent of CNT load and crystallization temperature. The study demonstrated CNTs' specific role in expediting the α-phase development in PP during isothermal crystallization experiments. Additionally, the investigation into MWCNTs within PP nanocomposites highlighted a pivotal percolation threshold at 0.5% (by weight) MWCNTs. Below this threshold, enhancements in physical properties were observed without requiring a compatibilizer. Augmented interfacial area between PP and MWCNTs notably enhanced PP's thermal stability, particularly evident at elevated temperatures, with heat-treated fibers exhibiting a distinct, narrow melting peak at 170 °C. These novel discoveries significantly advance our understanding of how CNTs impact PP crystallization and underscore the development of superior PP nanocomposites endowed with heightened thermal properties, catering to targeted applications demanding superior performance.