The thermal degradation of bisphenol A polycarbonate in air

• Published in: Thermochimica acta Vol. 426; no. 1; pp. 73 - 84
• Main Authors: Jang, Bok Nam, Wilkie, Charles A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2005; Elsevier Science
• Subjects: Applied sciences; Bisphenol; Chemical reactions and properties; Degradation; Exact sciences and technology; Isopropylidene linkage; Organic polymers; Peroxides; Physicochemistry of polymers; Thermal degradation; Isopropylidene linkage; Peroxides; Bisphenol; Thermal degradation; Pyrolysis; Fourier transformation; Coupled method; Thermogravimetry; Air; Infrared spectrometry; Bisphenol A; Gas chromatography; Thermal analysis; Polycarbonate; Mass spectrometry; Organic peroxide
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2004.07.023

The thermal degradation of polycarbonate in air was studied as a function of mass loss using TGA/FTIR, GC/MS and LC/MS. In the main degradation region, 480–560 °C, the assigned structures of smaller molecules and linear molecules that evolved in air were very similar to those obtained from the degradation in nitrogen; the degradation of polycarbonate follows chain scission of the isopropylidene linkage, in agreement with the bond dissociation energies, and hydrolysis/alcoholysis of carbonate linkage. Compared to the degradation in nitrogen, some differences were observed primarily in the beginning stage of degradation. Oxygen may facilitate branching as well as radical formation via the formation of peroxides. These peroxides undergo further dissociations and combinations, producing aldehydes, ketones and some branched structures, mainly in the beginning stage of degradation. It is speculated that the intermediate char formed in the beginning due to branching reactions of peroxide interferes with the mass transfer through the surface of degrading polycarbonate in the main degradation. Thus, even though the mass loss begins earlier in air, a slower mass loss rate is observed.