Author : Gökçen Alev Altun Çiftçioğlu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (85 download)
Book Synopsis Mathematical Modeling and Simulation of Photopolymerization Process by : Gökçen Alev Altun Çiftçioğlu
Download or read book Mathematical Modeling and Simulation of Photopolymerization Process written by Gökçen Alev Altun Çiftçioğlu and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Stereolithography is a method which produces any object of complex geometry with desired qualities from its computer aided design. The production in stereolithography method is realized by the free-radical photopolymerization reaction. Therefore, a computer controlled ultraviolet (UV) light source is used to turn a liquid resin into a solid object of desired geometry in relatively short time. This method is rapidly growing into a multibillion dollar industry with applications in many fields such as electronics, medicine, aerospace, and transportation. However, the photopolymerization as the fundamental process of stereolithography production is not yet well understood. For this reason it is continuing to be an interesting active research subject today .The main purpose of this study is to develop mathematical models to contribute to the understanding of the reaction kinetics of the photopolymerization process and to make reliable simulations ofthe process. For this purpose, the first model was developed by using a system of two-dimensional partial differential equations to describe the heat and mass transfer effects in addition to the basic polymerization reactions: initiation, propagation, termination, and inhibition. The second model used one-dimensional coupled nonlinear ordinary differential equations describing the change in the concentration of various polymeric species in the reaction volume. The rate constants used for the termination reactions in this model is determined by considering the chain-length of the polymeric species . involved in the reactions. The effects of the free volume and the diffusion on the reaction kinetics in this model are taken into account via both the propagation and termination rate constants. In experiments conducted in stereolithography , the resin was prepared from four functional ethoxylated pentaerythritol tetraacrylate (SR494) monomer mixing with high absorbance capacity photoinitiator molecule of 2% by weight. The liquid resin surface was illuminated by the uv light source moving under the control of the computer in experiments conducted in stereolithography apparatus and the change in the dimensions ofthe solid objects produced with different uv light scanning speeds were measured. The dimensions ofthese solid objects were calculated by solving the model based on the two-dimensional partial differential equations and the results found were determined to be in good agreement with the experimental results. Gelation point in photopolymerization process is referred to as the point where the liquid resin begins to cure or solidify , causing the resin viscosity to increase rapidly . The time elapses for the photopolymerization process to reach to this point is called the gelation time. The determination of the gelation time is very important for productions using stereolithography technique. In this study , the effects of the resin type, the concentration of photoinitiator, and the properties of uv light (wavelength.
