almost depleted of carbonate functionalities, was noticed. Webb and Czanderna (1986) postulated that this cross-linked structure could be the result of photophysical interactions between car- bonate and phenol groups formed from the photoageing. These interactions involved an energy transfer from the phenolic group to the adjacent hydrogen-bonded carbonyl and consequently an abstraction of the phenolic proton by the excited carbonyl. The resulting radical is likely to form a cross-linked structure. Moreover, Ramani and Ranganathaiah (2000) in a viscosity measurement on UV irradiated PC report the change in molecular weight due to chain scission and partial cross-linking. However, from our data we can conclude that the glass transition temperature of the aged samples seems not to depend neither on the number of reprocessing cycles nor on the residence time in the QUV chamber.