Preprint Article Version 1 This version is not peer-reviewed

Modeling Strategy for 3-Wavelength (UV, Blue, Red) Controlled Photopolymerization: Part-II, Improved Conversion and Confinement in 3D-Printing

Version 1 : Received: 3 November 2019 / Approved: 4 November 2019 / Online: 4 November 2019 (03:16:16 CET)

How to cite: Lin, J.; Cheng, D.; Chen, K.; Chiu, Y.; Liu, H. Modeling Strategy for 3-Wavelength (UV, Blue, Red) Controlled Photopolymerization: Part-II, Improved Conversion and Confinement in 3D-Printing. Preprints 2019, 2019110032 (doi: 10.20944/preprints201911.0032.v1). Lin, J.; Cheng, D.; Chen, K.; Chiu, Y.; Liu, H. Modeling Strategy for 3-Wavelength (UV, Blue, Red) Controlled Photopolymerization: Part-II, Improved Conversion and Confinement in 3D-Printing. Preprints 2019, 2019110032 (doi: 10.20944/preprints201911.0032.v1).

Abstract

Detailed kinetics for a 3-wavelength photopolymerization confinement (PC) system is presented for both numerical solutions and analytic formulas. The dynamic profiles are simulated for oxygen, free radical, and conversion for various situations of: blue-light only, 2-light (red and UV), and 3-light (red, blue, UV). An effective PC requires two conditions: (i) a strong N-inhibition for uncured regime with a low conversion (triggered by the UV-light); and (ii) a weak S-inhibition (oxygen-induced) for high conversion under the blue-light or blue and red-light initiation. Good PC candidates are governed by collective factors of: (i) the double ratio of light-intensity and initiator-concentration, (ii) monomers rate-constant; and (iii) effective absorption constants at specific wavelength and initiators. A new reverse feature for the role of N-inhibition on the blue-conversion is found. Higher oxygen concentration leads to a lower conversion, which could be enhanced by reducing the S-inhibition via a red or blue-light pre-irradiation, having a pre-irradiation time TP=200 s for red-light only, and reduced to 150 s, when both red and blue-light. System under UV-only leads a conversion lower than that of blue-only. However, conversion could be improved by the dual-light (blue and UV), and further enhanced by the pre-irradiation of red-light. The two competing factors, N-inhibition and S-inhibition, could be independently and selectively tailored to achieve: (a) high conversion of blue-light (without UV-light), enhanced by red-light pre-irradiation for minimal S-inhibition; and (b) efficient PC initiated by UV-light produced N-inhibition for reduced confinement thickness and for high print speed.

Subject Areas

kinetic model; 3-wavelength; photopolymerization; spatial confirmation; additive manufacturing; 3D printing

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