Determination of the Thermal Decomposition Products of Terephthalic Acid by Using Curie- Point Pyrolyzer

The thermal decomposition behavior of terephthalic acid (TA) was investigated by thermogravimetry/differential thermal analysis (TG/DTA) and Curie-point pyrolysis. TG/DTA analysis showed that TA is sublimed at 276 degrees C prior to decomposition. Pyrolysis studies were carried out at various temperatures ranging from 160 to 764 degrees C. Decomposition products were analyzed and their structures were determined by gas chromatography-mass spectrometry (GC-MS). A total of 11 degradation products were identified at 764 degrees C, whereas no peak was observed below 445 degrees C. Benzene, benzoic acid, and 1,1-biphenyl were identified as the major decomposition products, and other degradation products such as toluene, benzophenone, diphenylmethane, styrene, benzaldehyde, phenol, 9H-fluorene, and 9-phenyl 9H-fluorene were also detected. A pyrolysis mechanism was proposed based on the findings.