FTIR investigation of structural modifications during low-temperature ageing of polycarbonate

Conformational changes are sought during low-temperature ageing of solution-cast films of BPA-polycarbonate, by observing the conformationally sensitive IR aromatic breathing band at 1600 cm−1. Preliminary results using the carbonyl band at 1775 cm−1 had shown some indication of ageing-induced changes in the distribution of conformations. The present results obtained on the 1600 cm−1 band show no indication whatever of conformational rearrangements. This result, at variance with observations of conformational rearrangements accompanying sub-Tg annealing, lends support to the concept that sub-Tg annealing and low temperature ageing are two distinct processes.