Pyrene Fluorescence as a Probe for the Monitoring of Polymerization Processes: Simultaneous DSC and Fluorescence Study

The polymerization of cyclohexylmethacrylate was monitored, over a wide temperature range, by simultaneous differential scanning calorimetry (DSC) and fluorimetry (FL); the equipment for both being optically coupled. Pyrene was used as a fluorescent probe. There was excellent agreement between the exothermic peak time obtained by DSC and the time at which the maximum gradient was obtained in the fluorescence intensity-time curves, but only for temperatures above 60°C. Activation energies for the gel effect onset were obtained for both, the conversion-time and intensity-time curves being concordant except for data at low temperatures, below 60°C. It was concluded that vitrification occurs at temperatures below 60°C and its presence was demonstrated by fluorimetry, by means of the conversion change associated with the fluorescence intensity jump Δα(off-on).