reduction in the molecular weight took place. The fact that the molecular weight did not practically change from the first residence period, may be because the degradative effect for low molecular weight molecules is less pronounced or due to cross-linking reactions which minimize the degradative effect. In fact, Abbas (1981) and Bai et al. (2007) reported cross-linking processes in the PC degradation. These authors suggest that cross-linking among the PC molecules can take place during the sample reprocessing degra- dation processes.