Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9694238 | Thermochimica Acta | 2005 | 12 Pages |
Abstract
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.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Bok Nam Jang, Charles A. Wilkie,