Letters: Television signal-to-noise ratio before and after demodulation

Eaton, J.L.; Osborne, B.W.

doi:10.1049/ree.1979.0028

Cited by 3 publications

(7 citation statements)

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“…In contrast, NPG shows high proton transfer efficiency of the radical/cation because once NPG donates an electron, the radical/cation of NPG formed by electron transfer decomposes rapidly to yield CO 2 , a proton and a radical fragment 16,18,27,28 as shown in Figure 7. From the unusual unimolecular fragmentation reaction, NPG demonstrates extremely high proton transfer efficiency and the decarboxylation of the radical/cation of N-phenyl-substituted amino acid is extremely rapid.…”

Section: Resultsmentioning

confidence: 99%

“…This result is consistent with the reported trends for reduced activity in MB/NPG initiated polymerizations. 14,16 The decarboxylation of the radical/cation of the N-phenyl-substituted amino acid is extremely rapid, which is very effective for initiation kinetics but also lead to decreased shelflife. Thus, MB/NPG/DPI demonstrates an extremely high proton transfer efficiency but provides a poor shelf-life time.…”

Section: à52mentioning

confidence: 99%

“…14,16 Alternatively, a lack of photoinitiator stability can result in premature polymerization. In addition, it is notable that the interaction of a nucleophilic electron donor with a dye may lead to loss of initiator efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, it is notable that the interaction of a nucleophilic electron donor with a dye may lead to loss of initiator efficiency. [15][16][17][18] The photoinduced electron transfer process that produces active centers may, in many cases, also be thermally induced in the dark. 15 Therefore, the thermal stability and shelf life of fully formulated multi-component visible-light initiator systems in monomer is often less than that for the corresponding UV-activated material.…”

Section: Introductionmentioning

confidence: 99%

“…15,16 Dark polymerization reactions between electron donor and the dye, the monomer, or other components of these systems often occur because the nucleophilic electron donor can deprotonate the dye, thereby changing its absorption spectrum and electron transfer characteristics. 15 For these reasons, many visible-light-induced initiator systems do not meet shelf-life stability requirements.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the electron donor structure on the shelf‐lifetime of visible‐light activated three‐component initiator systems

Kim

Scranton

Stansbury

2009

J of Applied Polymer Sci

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In this study, we investigated the effect of electron donor structures on the shelf life of three-component initiator systems which also included methylene blue (MB) as a photosensitizer and diphenyl iodonium salt (DPI) as an electron acceptor. For this research, N-phenylglycine (NPG), N-methyldiethanolamine (MDEA), N,N-diisopropyl-3-pentylamine (DIPA), and 1,4-diazabicyclo[2.2.2]octane (DABCO) were used as electron donors, with different of proton transfer efficiencies and radical/cation persistence. To aid characterization of the shelf-life or dark storage stability of threecomponent initiator systems, the relative polymerization kinetic profile of each freshly prepared initiator system was first obtained using photo-DSC. The standardized photopolymerization reactions were repeated after various dark storage intervals. Thermal stability of each initiator system was compared by applying a ramped temperature program to monomer samples in the DSC in the dark. To analyze the kinetic changes as a function of storage time more quantitatively, we suggested an equation and characterized the shelflifetime constant (k) of three-component initiator systems.From the experiments and analysis, we conclude that the order of shelf-life is consistent with the of radical cation (DHÁ þ ) persistence; DABCO > DIPA > MDEA > NPG, and inversely related to the proton transfer efficiency of the electron donor; NPG > MDEA > DIPA > DABCO. The effects of electron donor structures on thermal stability were consistent with the results of kinetic shelf-life experiments. This investigation provides an effective means to characterize as well as predict shelf lifetimes of initiator systems.

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Section: Resultsmentioning

confidence: 99%

Section: à52mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%