Kinetic Features of Radical Dissociation in Filled Acetyl Cellulose

Davydov, E. Ya.; Pustoshnyi, V. P.; Vorotnikov, A. P.; Pustoshnaya, L. S.; Pariyskii, G. B.; Заиков, Г. Е.

doi:10.1080/00914030008035066

Cited by 3 publications

(8 citation statements)

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“…This is also evidenced by the results of measurement of the temperature dependence of the correlation time of the spin probe rotation. 99,100 The effective activation energy of the probe rotary mobility increased from 4.6 kJ mol 71 in non-filled CTA to 7.6 kJ mol 71 in CTA containing 60 mass % of Aerosil, i.e., filling has a substantial effect on the molecular dynamics and hence on the ratio of rate constants in individual stages of the radical process.…”

Section: Kinetic Features Of the Dissociation Of Radical Dimers In Fi...mentioning

confidence: 99%

“…A characteristic feature of cage reaction (4) of low-temperature decay of carbenes in solid polymers is the kinetic non-equivalence of species. 49 The time dependence of carbene concentration (N) is described by the following expression:…”

Section: The Effect Of Spatial Orientation Factors On the Decay Kinet...mentioning

confidence: 99%

“…Structural modification of polymers upon their filling is reflected in the kinetics of other elementary reactions, in particular of the monomolecular decay of macroradicals. Thus it was found that the kinetics of the radical decay of polyvinylpyrrolidone (PVP) initiated by photoreduction of Fe(III) additives at 77 K 49,91,92 is dependent on the presence of a filler.…”

Section: Effect Of the Filler On The Transformation Kinetics Of Macro...mentioning

confidence: 99%

“…However, kinetic studies of the DPE-free radicals system in CTA at 320 ± 370 K pointed to a more complex mechanism of this reaction in the solid polymer matrix. 99,100 In the temperature range 320 ± 334 K this process follows the scheme In the first step, dissociation of DPE yields RP. The rigid cage surrounding it prevents the exit of radicals from the cage.…”

Section: Kinetic Features Of the Dissociation Of Radical Dimers In Fi...mentioning

confidence: 99%

“…Temperature dependences of the yield of macroradicals 4 in the Aerosil-free (1) and Aerosil-filled (2, 3) PVP. The filler content (mass % ): 15 (2), 50 (3) 92.…”

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confidence: 99%

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Application of radical cage reactions in studies of microstructures of polymers and composites

Davydov¹,

Vorotnikov²,

Pustoshnyi³

et al. 2000

Russ. Chem. Rev.

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Overlayers of a fatty acid (palmitic and lauric acid) formed at the interface between a solution of this molecule in phenyloctane and the basal plane of graphite are studied by in situ scanning tunnelling microscopy. The layers organize into lamellae, which are formed by a close packing arrangement of molecules parallel to the graphite surface. Chemical modification of the STM tips used allowed identification of the functional group. Indeed, the gold tips used are functionalized with 4-mercaptobenzoic acid (4-MBA) and 4-mercaptotoluene (4-MT). The same functional group on a sample is then 'seen' as a dark and a bright spot when imaged with 4-MBA and 4-MT modified tips, respectively. This contrast distinction is related to interactions (or a lack of them) between the carboxyl group on the sample and molecules on the tip, which can facilitate (or hinder) the electron tunnelling.

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Section: Kinetic Features Of the Dissociation Of Radical Dimers In Fi...mentioning

confidence: 99%

Section: The Effect Of Spatial Orientation Factors On the Decay Kinet...mentioning

confidence: 99%

Section: Effect Of the Filler On The Transformation Kinetics Of Macro...mentioning

confidence: 99%

Section: Kinetic Features Of the Dissociation Of Radical Dimers In Fi...mentioning

confidence: 99%

“…Temperature dependences of the yield of macroradicals 4 in the Aerosil-free (1) and Aerosil-filled (2, 3) PVP. The filler content (mass % ): 15 (2), 50 (3) 92.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Application of radical cage reactions in studies of microstructures of polymers and composites

Davydov¹,

Vorotnikov²,

Pustoshnyi³

et al. 2000

Russ. Chem. Rev.

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Semiempirical Equations for Modeling Solid-State Kinetics Based on a Maxwell−Boltzmann Distribution of Activation Energies: Applications to a Polymorphic Transformation under Crystallization Slurry Conditions and to the Thermal Decomposition of AgMnO₄ Crystals

2005

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Many solid-state reactions and phase transformations performed under isothermal conditions give rise to asymmetric, sigmoidally shaped conversion-time (x-t) profiles. The mathematical treatment of such curves, as well as their physical interpretation, is often challenging. In this work, the functional form of a Maxwell-Boltzmann (M-B) distribution is used to describe the distribution of activation energies for the reagent solids, which, when coupled with an integrated first-order rate expression, yields a novel semiempirical equation that may offer better success in the modeling of solid-state kinetics. In this approach, the Arrhenius equation is used to relate the distribution of activation energies to a corresponding distribution of rate constants for the individual molecules in the reagent solids. This distribution of molecular rate constants is then correlated to the (observable) reaction time in the derivation of the model equation. In addition to providing a versatile treatment for asymmetric, sigmoidal reaction curves, another key advantage of our equation over other models is that the start time of conversion is uniquely defined at t = 0. We demonstrate the ability of our simple, two-parameter equation to successfully model the experimental x-t data for the polymorphic transformation of a pharmaceutical compound under crystallization slurry (i.e., heterogeneous) conditions. Additionally, we use a modification of this equation to model the kinetics of a historically significant, homogeneous solid-state reaction: the thermal decomposition of AgMnO4 crystals. The potential broad applicability of our statistical (i.e., dispersive) kinetic approach makes it a potentially attractive alternative to existing models/approaches.

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Outstanding Advantages, Current Drawbacks, and Significant Recent Developments in Mechanochemistry: A Perspective View

Pagola

2023

Crystals

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Although known since antiquity, mechanochemistry has remained dormant for centuries. Nowadays, mechanochemistry is a flourishing research field at the simultaneous stages of gathering data and (often astonishing) observations, and scientific argumentation toward their analysis, for which the combination of interdisciplinary expertise is necessary. Mechanochemistry’s implementation as a synthetic method is constantly increasing, although it remains far from being fully exploited, or understood on the basis of fundamental principles. This review starts by describing many remarkable advantages of mechanochemical reactions, simplifying and “greening” chemistry in solutions. This description is followed by an overview of the current main weaknesses to be addressed in the near future toward the systematic study of its energetics and chemical mechanisms. This review finishes by describing recent breakthrough experimental advances, such as in situ kinetics monitoring using synchrotron X-ray powder diffraction and Raman spectroscopy, plus equally significant computational chemistry approaches, such as quantum mechanochemistry, used for the understanding of covalent or hydrogen bond ruptures in biomolecules or mechanophores in polymers at the single-molecule level. Combined with new technologies to control temperature and pressure in ball mills, these appealing new methods are promising tools for establishing the fundamental knowledge necessary for the understanding of mechanochemical reactivity and mechanisms.

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Kinetic Features of Radical Dissociation in Filled Acetyl Cellulose

Cited by 3 publications

References 1 publication

Application of radical cage reactions in studies of microstructures of polymers and composites

Application of radical cage reactions in studies of microstructures of polymers and composites

Semiempirical Equations for Modeling Solid-State Kinetics Based on a Maxwell−Boltzmann Distribution of Activation Energies: Applications to a Polymorphic Transformation under Crystallization Slurry Conditions and to the Thermal Decomposition of AgMnO₄ Crystals

Outstanding Advantages, Current Drawbacks, and Significant Recent Developments in Mechanochemistry: A Perspective View

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Kinetic Features of Radical Dissociation in Filled Acetyl Cellulose

Cited by 3 publications

References 1 publication

Application of radical cage reactions in studies of microstructures of polymers and composites

Application of radical cage reactions in studies of microstructures of polymers and composites

Semiempirical Equations for Modeling Solid-State Kinetics Based on a Maxwell−Boltzmann Distribution of Activation Energies: Applications to a Polymorphic Transformation under Crystallization Slurry Conditions and to the Thermal Decomposition of AgMnO4 Crystals

Outstanding Advantages, Current Drawbacks, and Significant Recent Developments in Mechanochemistry: A Perspective View

Contact Info

Product

Resources

About

Semiempirical Equations for Modeling Solid-State Kinetics Based on a Maxwell−Boltzmann Distribution of Activation Energies: Applications to a Polymorphic Transformation under Crystallization Slurry Conditions and to the Thermal Decomposition of AgMnO₄ Crystals