A thermosetting plastic material commercially known as CR-39 is widely used in optical applications. Thermal initiation with peroxides is used in the conventional process. Because of the highly exothermic nature of the reaction, it must be carried out at extended periods of time and at relatively low temperature to avoid defects in the final material, especially for the fabrication of thick lenses. The use of a non-thermal initiation process, such as with UV radiation-sensitive photoinitiators, allows a faster polymerization and reduces the exothermic effects; on the other hand, the high reaction rates and the resulting exothermic effects can cause defects in the lenses. The knowledge of the conversion and temperature profiles within the thick material during polymerization is essential for the optimization of both processes. In this work models are studied to simulate those processes. The mass and energy balances result in partial differential equations that are solved by orthogonal collocation and Runge-Kutta-Gill methods.
Modeling and simulation; lenses; photopolymerization; CR-39
