Flame-Retardant Polypropylene/Multiwall Carbon Nanotube Nanocomposites: Effects of Surface Functionalization and Surfactant Molecular Weight

Flame-retardant polypropylene (PP)/carbon nanotubes (CNTs) nanocomposites influenced by surface functionalization and surfactant molecular weights are studied. 3-Aminopropyl-triethoxysilane (APTES) is utilized to modify the CNTs (f-CNTs), and maleic-anhydride-grafted PP (MAPP) with two molecular weights ((M)over bar(n) of 800 and 8000 g mol(-1)) is used to further improve the dispersion of f-CNTs in the PP matrix. Thermal gravimetric analysis (TGA) and microscale combustion calorimetry (MCC) reveal that the molecular weight of MAPP directly affects the thermal stability and flammability of PP/f-CNTs PNCs: both MAPP polymers ((M)over bar(n) of 800 and 8000 g mol(-1)) increase the thermal stability of PP; however, the heat release rate of PP/fCNTs is reduced in the presence of MAPP ((M)over bar(n) of 800 g mol(-1)) and increased in the presence of MAPP ((M)over bar(n) of 8000 g mol(-1)). MAPP ((M)over bar(n) of 800 g mol(-1)) also results in a lower viscosity of the PP/f-CNTs PNCs compared with pure PP.