Mechanism of the inhibiting action of phosphites and sulfides

Pobedimskii, D. G.; Бучаченко, А. Л.

doi:10.1007/bf00907777

Cited by 8 publications

(9 citation statements)

References 6 publications

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“…We can assume that ρ h is proportional to the π-electron spin density at the halogen-substituted carbon of the donor cation radical. Spin densities of DMA •+ estimated from the EPR spectrum are shown in Figure . Since the spin densities are very small at the 3 and 5 positions, the SOC interaction due to the bromine atom is too weak to create sufficient A polarization over the E-TM in the DQ-3BrDMA system.…”

Section: Discussionmentioning

confidence: 99%

Spin−Orbit Coupling Induced Electron Spin Polarization: Influence of Heavy Atom Position

et al. 1997

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Echo-detected FT-EPR spectra have been observed for the quinone anion radical generated from the photoexcitation of duroquinone (DQ) in the presence of N,N-dimethylaniline (DMA) and its monohalogen substituents in 1-propanol. When DMA and 4-Cl DMA were used as the electron donor, the net-emissive polarization due to a triplet mechanism was observed. In contrast, the electron donors of 4-BrDMA and 4-IDMA gave unusual net-absorptive (A) CIDEP spectra of the DQ anion radical at the delay time of 200 ns between the laser and first microwave pulses. It was found that the enhancement factor of the net-A polarization remarkably depends on the heavy atom position in the donor. The net-A polarization observed is attributable to a spin−orbit coupling mechanism (SOCM). Simple explicit expressions have been given for the electron spin polarization generation due to SOCM.

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Section: Discussionmentioning

confidence: 99%

Spin−Orbit Coupling Induced Electron Spin Polarization: Influence of Heavy Atom Position

et al. 1997

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“…In fact, this radical mechanism leads to efficient stabilization only if the radicals do not escape from the cage. This, according to Pobeminskii and Buchachenko, is in fact the case [4]. Nevertheless, recent research on polyethylene oxidation [5] indicates that even macroradicals are capable of escaping from the cage and this in turn makes this particular radical mechanism questionable.…”

Section: Introductionmentioning

confidence: 99%

Modelling of thermal oxidation of phosphite stabilized polyethylene

Djouani

Richaud

Fayolle

et al. 2011

Polymer Degradation and Stability

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Modelling of thermal oxidation of phosphite stabilized polyethylene. Polymer Degradation and Stability, Elsevier, 2011, 96 (7), pp. a b s t r a c tThe thermal oxidation behaviour of polyethylene films stabilized by various weight ratios of organophosphites (Irgafos 168) has been studied at selected temperatures. The duration of the induction period was found to increase proportionally with the stabilizer concentration, even at temperatures as low as 80 C. Particular attention was paid to the phosphiteephosphate conversion during the induction period. A kinetic model, involving volatile and partially soluble hydroperoxide decomposers, was developed in order to simulate these results. With the use of kinetic parameters that can be at least tentatively justified from theoretical considerations, this model gave simulations in reasonable agreement with the experimental observations for stabilizer depletion and carbonyl formation. Of particular note is the fact that, even for non-trivial results such as the shape of the phosphite versus phosphate concentration plots, or phosphate build-up, there was also a quite good agreement.

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“…In addition, these stabilizing sacrificial functions can be chosen to give new sulfonic acid groups once oxidized (thiols, disulfides, etc. ), − therefore increasing the concentration of acid groups in the membrane and improving its proton conductivity. These hybrid membranes should then exhibit excellent chemical and thermomechanical stability, excellent water retention, and therefore excellent proton conduction at low relative humidity.…”

Section: Introductionmentioning

confidence: 99%

Untangling the Condensation Network of Organosiloxanes on Nanoparticles using 2D ²⁹Si–²⁹Si Solid-State NMR Enhanced by Dynamic Nuclear Polarization

et al. 2014

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Silica (SiO2) nanoparticles (NPs) were functionalized by silanization to produce a surface covered with organosiloxanes. Information about the surface coverage and the nature, if any, of organosiloxane polymerization, whether parallel or perpendicular to the surface, is highly desired. To this extent, two-dimensional homonuclear (29)Si solid-state NMR could be employed. However, owing to the sensitivity limitations associated with the low natural abundance (4.7%) of (29)Si and the difficulty and expense of isotopic labeling here, this technique would usually be deemed impracticable. Nevertheless, we show that recent developments in the field of dynamic nuclear polarization under magic angle spinning (MAS-DNP) could be used to dramatically increase the sensitivity of the NMR experiments, resulting in a timesaving factor of ∼625 compared to conventional solid-state NMR. This allowed the acquisition of previously infeasible data. Using both through-space and through-bond 2D (29)Si-(29)Si correlation experiments, it is shown that the required reaction conditions favor lateral polymerization and domain growth. Moreover, the natural abundance correlation experiments permitted the estimation of (2)J(Si-O-Si)-couplings (13.8 ± 1.4 Hz for surface silica) and interatomic distances (3.04 ± 0.08 Å for surface silica) since complications associated with many-spin systems and also sensitivity were avoided. The work detailed herein not only demonstrates the possibility of using MAS-DNP to greatly facilitate the acquisition of 2D (29)Si-(29)Si correlation spectra but also shows that this technique can be used in a routine fashion to characterize surface grafting networks and gain structural constraints, which can be related to a system's chemical and physical properties.

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Mechanism of the inhibiting action of phosphites and sulfides

Cited by 8 publications

References 6 publications

Spin−Orbit Coupling Induced Electron Spin Polarization: Influence of Heavy Atom Position

Spin−Orbit Coupling Induced Electron Spin Polarization: Influence of Heavy Atom Position

Modelling of thermal oxidation of phosphite stabilized polyethylene

Untangling the Condensation Network of Organosiloxanes on Nanoparticles using 2D ²⁹Si–²⁹Si Solid-State NMR Enhanced by Dynamic Nuclear Polarization

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Mechanism of the inhibiting action of phosphites and sulfides

Cited by 8 publications

References 6 publications

Spin−Orbit Coupling Induced Electron Spin Polarization: Influence of Heavy Atom Position

Spin−Orbit Coupling Induced Electron Spin Polarization: Influence of Heavy Atom Position

Modelling of thermal oxidation of phosphite stabilized polyethylene

Untangling the Condensation Network of Organosiloxanes on Nanoparticles using 2D 29Si–29Si Solid-State NMR Enhanced by Dynamic Nuclear Polarization

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Product

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Untangling the Condensation Network of Organosiloxanes on Nanoparticles using 2D ²⁹Si–²⁹Si Solid-State NMR Enhanced by Dynamic Nuclear Polarization