Surface engineering of carbon nanotubes towards the improvement of flame retardant of polymer nanocomposites

This chapter examines the surface modification of carbon nanotubes (CNTs) aimed at improving the flame-retardant characteristics of polymer nanocomposites. Carbon nanotubes are recognized for their remarkable mechanical, electrical, and thermal attributes, which significantly enhance flame resistance when integrated into polymer matrices. Nonetheless, their propensity to clump together due to strong van der Waals interactions poses a challenge to their efficacy. The chapter delves into noncovalent functionalization methods that facilitate better dispersion of CNTs while preserving their inherent properties. By employing surfactants, polymers, or small molecules, these techniques enhance the compatibility of CNTs with polymer matrices, resulting in more uniform dispersion and enhanced reinforcement. The chapter also discusses essential characterization techniques, including FTIR and Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and thermal analysis methods such as thermogravimetric analysis and differential scanning calorimetry, to assess the functionalization and distribution of CNTs within polymer matrices. The chapter also reviews the mechanisms by which CNTs enhance flame retardancy, including promoting char formation, heat dissipation, and improving polymer mechanical properties. Flame retardancy assessments, including cone calorimetry, limiting oxygen index (LOI), and UL-94 tests, are used to evaluate the performance of CNT-based nanocomposites. The environmental impact of traditional flame retardants and their effects on polymer properties are also addressed, underscoring the importance of CNTs as an eco-friendlier alternative for enhancing flame retardancy in polymers. This chapter concludes with insights into optimizing surface-engineered CNTs for advanced flame-retardant applications.