Kinetics of Photopolymerization for Laser Cured Resins
Date Issued
2012
Date
2012
Author(s)
Cheng, Kuei-Ta
Abstract
The kinetics of photopolymerization of thick photosensitive resins illuminated by a focused Gaussian beam was studied theoretically. The polymerization rate is a function of the absorbance and concentration of the photoinitiator. Meanwhile, the light intensity distribution may also have strong effects on the shape of the polymerized resins. In this thesis, several kinetic coupling equations are solved to simulate the curing process of polymerization. The temporal and spatial photopolymerization process could be simulated quantitatively. In the past, the light source used in the dental restorations was close to the diverged plane wave. The incident light will be absorbed by surface or shallow materials, and light intensity in the deep materials attenuates rapidly. Therefore, we get an uneven polymerized resins which have non-ideal biological functions. We use a focused Gaussian beam to compensate for the light intensity attenuation caused by absorption of the surface or shallow materials, and we make the initial light intensity on the surface the same as the initial light intensity on the bottom. With a proper control of the characteristics of a focused Gaussian beam such as the light intensity, focusing distance, and beam waist, a nearly uniform polymerized resins can be achieved. As long as we know the polymerization threshold value (the concentration of monomers reduced to a specific percentage of the initial concentration), the propagation constant and the termination constant of radical chain polymerization, we could estimate quantitatively the completion time of polymerized resins by a simple equation. The theoretical results would be useful for designing the light sources for the medical and industrial applications using thick photopolymers.
Subjects
photopolymerization
laser cured resins
dental restoration
Type
thesis
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