Modeling the kinetics of enhanced photo-polymerization under a collimated and a reflecting focused UV laser

Abstract

This study explored the kinetics of ultraviolet (UV) laser photoinitiatedpolymerization in thick polymer systems to achieve improved polymerization efficiencyand uniformity. The modeling system comprised an incident UV laser and its reflectingbeam, which was focused by a concave mirror to compensate for the exponential decay inthe absorbing medium. The polymerization kinetic equation was numerically solved for theinitiator concentration. The crossover time was calculated and compared among singlebeam, two collimated beam and collimated plus reflecting focused-beam systems. For thesingle beam case, analytic formulas for the time dependent incident beam is derived anddemonstrated by measured data. A theoretical crossover time is defined to analyze themeasured data based on the dynamic moduli. Lastly, the polymerization boundarydynamics are illustrated, showing the advantage of the combined two beam system. Thenumerical results provide useful guidance and a novel means for accelerated uniformphoto-polymerization, which cannot be achieved by other means. © 2014 by the authors; licensee MDPI, Basel, Switzerland.