In this study, light irradiations were performed at a temperature
of 60 C. It can be expected that, at this temperature, camphor can
migrate from the polymer to the gas phase within the duration of
the experiments (50 h of exposure in the artificial accelerated
photoageing device). The loss of camphor explains the decrease of
the ketone band. Aged samples of celluloid in museum storage and
exhibition also revealed a loss of camphor [16].