Photoinitiation Rate Profiles during Polymerization of a Dimethacrylate-based Resin.

SILVANA ASMUSSEN; GUSTAVO ARENAS; WAYNE D. COOK; CLAUDIA VALLO

EUROPEAN POLYMER JOURNAL

Elsevier

Año: 2009 vol. 45 p. 515 - 522

0014-3057

The photodecomposition of Camphorquinone (CQ) was measured by monitoring the decrease in light absorption as a function of irradiation time. Measurements were carried out during photopolymerization under continuous irradiation of a Dimethacrylate-based resin photoactivated with CQ/amine. The kinetics was satisfactory fitted to a first order expression and the rate constant was proportional to the irradiation intensity. Gradients of photoinitiator concentration, light intensity and photoinitiation rate along the path of irradiation were calculated by solving the coupled system of equations that describe the photoinitiator decomposition rate and light attenuation according to the integrated form of the Beer’s law. The photodecomposition reaction was spatially inhomogeneous and the degree of nonunuformity increased with increased initial sample absorbance. The influence of the photobleaching process on the polymerization reaction was examined. The photobleaching rate of CQ was much slower than the polymerization rate and only 20 % of the initial amount of CQ was consumed before the polymerization reaction had almost ceased. Results obtained in this research highlight the inherent interlinking of light attenuation and photobleaching rate in bulk polymerizing systems.