DSC INVESTIGATIONS ON A COMMERCIAL PHOTOCURING SHEET MATERIAL

The photopolymerization of a commercial sheet material as used in the dental laboratory was investigated by using the photocalorimeter DSC7/ DPA7 (Perkin-Elmer). Using normal reaction conditions (light wavelengt h less than or equal to 400 nm, light intensity greater than or equal to 1 mW cm(-2) and sample thickness less than or equal to 2.5 mm), the curing was completed within few min. The reaction rate was nearly ind ependent on the light wavelength in the range between lambda=300 and 3 80 nm, but decreased distinctively at longer wavelenghts. After desmea ring the DSC curves, the dependence of the reaction rate on light inte nsity and sample thickness could be described in very good approximati on by an equation derived by Tryson [1]. Comparable with pure acrylate s or methacrylates, a pronounced dark reaction was found after interru ption of the illumination.