Volume 46, Number 5  (September - October 2001)

Key words:  gas chromatography-mass spectrometry, poly(ethylene terephthalate), PET thermal degradation, plastics thermal degradation

The composition of smoke emitted during thermal degradation of poly(ethylene terephthalate) (PET) was analyzed by capillary gas chromatography with mass selective detector (GC-MS). Thermal degradation of PET was carried out in a tubular furnace under nitrogen flow at 200, 300, 400, 500, 600 and 700 ^oC for 20 min. The less-volatile compounds evolved from PET were trapped on a glass fiber and extracted with methanol. During the degradation of PET at lower temperatures (200-300 ^oC) the emission of smoke was not observed. Whithin the temperature range of 400-700 ^oC the thermal degradation process was accompanied by the emission of the less-volatile compounds forming a pale yellow smoke. The analyses have shown, that the emitted smokes are the complex mixture of aromatic compounds, including terephthalic acid and its esters, benzoic acid, p-substituted benzoic acid, 2-naphtoic acid, 1,4-diacetyl-benzene, 4-acetylbiphenyl, oligomers of PET, traces of polycyclic aromatic hydrocarbons and dibutyl phthalate. The temperature influence on the emission and composition of the smoke evolved from PET was studied.