scholarly journals Efficacy Modeling of New Multi-Functional Benzophenone-Based System for Free-Radical/Cationic Hybrid Photopolymerization Using 405 nm LED

2021 ◽  
Author(s):  
Jui-Teng Lin ◽  
Jacques Lalevee
Keyword(s):  
Free Radical ◽  
Quantum Yield ◽  
Light Intensity ◽  
Absorption Coefficient ◽  
Light Absorption ◽  
Dual Function ◽  
Effective Absorption Coefficient ◽  
Component System ◽  
Effective Absorption ◽  
Increasing Function

This article presents, for the first time, the kinetics and the general conversion features of a 3-component system, BT(BC)/iodonium/Amine, based on proposed mechanism of Liu et al, for both free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using the new multi-functional initiator of benzophenone–triphenylamine (BT). The additives, iodonium and EDB, have the dual function of (i) regeneration BT and (ii) produce of extra radicals for improved FRP and CP. Analytic formulas are developed to explore the new features including: (i) the conversion efficacy (CE) of FRP is an increasing function of the light intensity, the effective absorption coefficient, and the concentration sum of each of the components, BT, Iod, amine, for transient state. However, CE at steady-state is independent to the light intensity; (ii) the trifunctional hybrid structures of BT3 leads to larger light absorption than other types of BT; it also provides more active sites for the H-abstraction in the presence of EDB, leading to high CE; (iii) the efficacy of FRP is an increasing function of the amine (EDB) concentration, in contrast to that of CP having an opposite dependence; (iv) the consumption rate of BT3 in the BT3/ Iod/EDB system is slower than that of the BT3/Iod system due to photoredox catalytic cycle, and the larger initiator regeneration (RGE)
in the three-component system. A comprehensive model is also proposed that the CE (for both FRP and CP) is governed by (NjKjbI), whereas more complex formulas are developed; where Kj is an effective rate constant proportional to the electron transfer quantum yield, and the combined effects of other coupling rate constants; b is an effective absorption coefficient given by the light absorption and excited state quantum yield.

scholarly journals Efficacy Analysis of Panchromatic New Copper Complex for Visible Light (455, 530 nm) Radical/Cationic Photopolymerization: The Synergic Effects and Catalytic Cycle

2021 ◽  
Author(s):  
Jui-Teng Lin ◽  
Jacques Lalevee ◽  
Da-Chun Cheng
Keyword(s):  
Free Radical ◽  
Light Intensity ◽  
Copper Complex ◽  
Catalytic Cycle ◽  
Nonlinear Dependence ◽  
Dual Function ◽  
Effective Absorption Coefficient ◽  
Oxygen Inhibition ◽  
New Findings ◽  
First Time

. This article presents, for the first time, the kinetics and the general conversion features of a 3-component system (A/B/N), based on proposed mechanism of Mau et al, for both free radical polymerization (FRP) of acrylates and the free radical promoted cationic polymerization (CP) of epoxides using various new copper complex (G2) as the initiator. Higher FRP and CP conversion can be achieved by co-additive of [B] and N, via the dual function of (i) regeneration [A], and (ii) generation of extra radicals. The FRP and CP conversion efficacy (CE) are proportional to the nonlinear power of bI[A][B], where b and I are the effective absorption coefficient and the light intensity, respectively. In the interpenetrated polymer network (IPN) capable of initiating both FRP and CP in a blend of TMPTA and EPOX, (as the monomer for FRP and CP, respectively), the synergic effects due to CP include:: (i) CP can increase viscosity limiting the diffusional oxygen replenishment, such that oxygen inhibition effects are reduced; (ii) the cationic monomer also acts as a diluting agent for the IPN network , and (iii) the exothermic property of the CP. Many new findings are explored via our analytical formuals include: (i) the CE of FRP is about twice of the CE of CP, due to the extra radicals involved in FRP; (ii) the catalytic cycle enhancing the efficacy is mainly due to the regenaration of the initiator, and (iii) the nonlinear dependence of light intensity of the CE (in both FRP and CP). For the first time, the catalytic cycle, synergic effects, and the oxygen inhibition are theoretically confirmed to support the experimental hypothesis. The measured results of Mau et al are well analyzed and matching the predicted features of our modeling. .

Information Content of AVHRR Channels 4 and 5 with Respect to the Effective Radius of Cirrus Cloud Particles

1991 ◽  
Vol 30 (7) ◽  
pp. 973-984 ◽  
Author(s):  
F. Parol ◽  
J. C. Buriez ◽  
G. Brogniez ◽  
Y. Fouquart
Keyword(s):  
Absorption Coefficient ◽  
Mean Value ◽  
Effective Radius ◽  
Forward Peak ◽  
Effective Absorption Coefficient ◽  
Brightness Temperatures ◽  
Microphysical Properties ◽  
Effective Absorption ◽  
Cloud Particles ◽  
The Relationship

Abstract This paper investigates the important difference in the relationship between brightness temperatures between the 11-μm and the 12-μn AVHRR data and the microphysical properties of the semitransparent cirrus clouds. In the nonscattering approximation, the emittance for channels 4 and 5 are related through the absorption coefficient ratio that is the key parameter giving access to the size of cloud particles. The observed mean value of this parameter corresponds to effective radius of 18 μm for polydisperse spheres and 12 μm for polydisperse infinitely long ice cylinders. Taking the multiple scattering into account, the brightness temperature difference enhances much more for cylinders than for spheres owing to the fact that the forward peak of scattering is less large for cylinders. To obtain the size of cloud particles, the method developed in the nonscattering case is still applicable if one makes use of the effective emittance that implicitly includes the effects of mattering. Thus, an effective absorption coefficient ratio is defined and we derive a direct relationship between this ratio and the optical properties of the cloud particles. The mean value of the effective absorption coefficient ratio corresponds to ice spheres of effective radius of 26 μm or a bit less in the case of water spheres (supercooled droplets), but no agreement can be obtained for fully randomly oriented cylinders.

Determination of the effective absorption coefficient for light in long plastic scintillators

1965 ◽  
Vol 2 (4) ◽  
pp. 242-244
Author(s):  
Yu. A. Tsirlin ◽  
A. R. Daich ◽  
T. I. Sokolovskaya ◽  
L. L. Nagornaya
Keyword(s):  
Absorption Coefficient ◽  
Effective Absorption Coefficient ◽  
Effective Absorption ◽  
Plastic Scintillators
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