Thermal oxidative degradation behaviours of flame-retardant copolyesters containing phosphorous linked pendent group/montmorillonite nanocomposites

A novel flame-retardant copolyester (PET-co-DDP)/organomontmorillonite (O-MMT) nanocomposite was synthesized by condensation of terephthalic acid (TPA), ethyleneglycol (EG), 9,10-dihydro-10[2,3-di(hydroxy carbonyl)propyl]10-phosphaphe-nanthrene-10-oxide (DDP) and O-MMT. PET-co-DDP is a flame-retardant copolyester containing phosphorous linked pendent groups. O-MMT was obtained by modifying MMT with octadecyltrimethylammonium chloride (1831) through cation exchange. The structure of the nanocomposite was characterized by wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The thermal oxidative degradation behaviour of PET-co-DDP/O-MMT nanocomposites was investigated via thermogravimetric (TG) analysis. The thermal oxidative degradation activation energies of the PET-co-DDP/O-MMT nanocomposites were determined using Kissinger, Flynn-Wall-Ozawa and Friedman methods, and were compared with those of PET-co-DDP copolyester. The results showed that adding MMT to PET-co-DDP increased the decomposition activation energy and the residues of the PET-co-DDP at high temperatures, showing the higher thermal stability of the nanocomposites.