Effect of MWCNTs and their modification on crystallization and thermal degradation of poly(butylene naphthalate)

In the present work, poly(butylene naphthalate) (PBN) and its nanocomposites containing pristine multi - walled carbon nanotubes (MWCNTs), as well as functionalized MWCNTs with amino and carboxyl groups (MWCNTs-NH₂ and MWCNTs-COOH), were in situ prepared by applying the melt polycondensation method. From transmission electron microscopy (TEM) images, it was found that functionalized MWCNTs exhibited better dispersion into the polymer matrix compared to pristine MWCNTs. The nanocomposites showed faster crystallization rates compared to the neat material as proved by differential scanning calorimetry (DSC), due to the nucleating effect of the fillers. Finally, the presence of nanotubes and especially MWCNTs and MWCNTs-NH₂ favored formation of α-crystals while for both neat PBN and PBN/MWCNTs-COOH β-crystals were also formed. Thermal stability of the nanocomposites, studied by thermogravimetric analysis (TGA), was significantly increased due to the presence of MWCNTs, while a detailed study of the kinetics of the decomposition process was performed by pyrolysis-gas chromatography–mass spectroscopy (Py-GC/MS).