A PROCESS MODEL FOR NONISOTHERMAL PHOTOPOLYMERIZATION WITH A LASER-LIGHT SOURCE .1. BASIC MODEL DEVELOPMENT

A mathematical model for a laser-induced photopolymerization process has been developed. This model simulates important aspects of stereolithography, a rapid prototyping process used for the production of three-dimensional plastic parts. The model consists of a set of coupled partial differential equations and considers irradiation, chemical reaction, and heat transfer in a small zone of material exposed to a stationary UV laser source. Numerical techniques are used for an approximate solution of the model equations, and the output includes spatial and temporal variations in the conversion of monomer to polymer, depletion of photoinitiator, and local variations of temperature in and around the region contacted by the laser light. Maximum conversions of approximately 60% and peak temperature rises of approximately 35-degrees-C were calculated for the cylindrical exposed region. Results have provided insights concerning laser dwell time, depth penetration, and the uniformity of polymer formed during the stereolithography process.