Ozonolysis of Natural Rubber: A Critical Review

Solanky, S. S.; Singh, Rajpal

doi:10.1177/147776060101700102

Cited by 17 publications

(3 citation statements)

References 60 publications

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“…The interest in the reaction of ozone with polydienes is due mainly to the problems of ozone degradation of rubber materials [1][2][3][4] and the application of this reaction to the elucidation of the structures of elastomers [5][6][7][8]. It is also associated with the possibilities of preparing bifunctional oligomers by partial ozonolysis of some unsaturated polymers [9][10][11][12]. Usually the interpretation of experimental results are based on a simplified scheme of Criegee's mechanism of C=Cdouble bond ozonolysis, explaining only the formation of the basic product -ozonides [13,14].…”

Section: Introductionmentioning

confidence: 99%

Ozone and its Reactions with Diene Rubbers

Заиков¹,

Rakovsky²,

Anachkov³

2012

ChChT

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The reactions of ozone with 1,4-cispolybutadiene (SKD); Diene 35 NFA (having the following linking of the butadiene units in the rubber macromolecules: 1,4-cis (47 %), 1,4-trans (42 %), 1,2-(11 %); 1,4-cis-polyisoprene (Carom IR 2200), 1,4-trans-polychloroprene (Denka M 40), and 1,4-transpolyisoprene have been investigated in CCl 4 solutions. The changes of the viscosity of the polymer solutions during the ozonolysis have been characterized by the number of chain scissions per molecule of reacted ozone (φ). The influence of the conditions of mass-transfer of the reagents in a bubble reactor on the respective φ values has been discussed. The basic functional groups-products from the rubbers ozonolysis have been identified and quantitatively characterized by means of IR-spectroscopy and 1 H NMR spectroscopy. A reaction mechanism that explains the formation of all identified functional groups has been proposed. It has been shown that the basic route of the reaction of ozone with elastomer double bondsformation of normal ozonides-does not lead directly to a decrease in the molecular mass of the elastomer macromolecules, because the respective 1,2,4-trioxolanes are relatively stable at ambient temperature. The most favourable conditions for ozone degradation emerge when the cage interaction between Criеgee's intermediates and respective carbonyl groups does not proceed. The amounts of measured different carbonyl groups have been used as an alternative way for evaluation of the intensity and efficiency of the ozone degradation. The thermal decomposition of partially ozonized diene rubbers has been investigated by DSC. The respective values of the enthalpy, the activation energy and the reaction order of the 1, 2, 4-trioxolanes have been determined.

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Section: Introductionmentioning

confidence: 99%

Ozone and its Reactions with Diene Rubbers

Заиков¹,

Rakovsky²,

Anachkov³

2012

ChChT

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“…Oxidative chemical degradation requires the use of specific oxidizing agents such as potassium persulfate, periodic acid, ozone, and others. ,− In addition, the indicated methods often involve several chemical steps. For instance, the direct ozonolysis of polydienes leads to the formation of FLRs that contain various functional groups (aldehyde, ketone, carboxylic, hydroxyl, hydroperoxide, and ozonide). − Therefore, an additional chemical treatment (e.g., reduction) is needed for their conversion into a certain type of functional group. − …”

Section: Introductionmentioning

confidence: 99%

The Effect of 1,2- and trans-1,4-Units on Ketonization of Polybutadienes by Nitrous Oxide

Semikolenov,

Ivanov,

Dubkov

2024

Ind. Eng. Chem. Res.

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Earlier it was shown that the oxygenation of double bonds in polydienes by nitrous oxide (N 2 O) via the 1,3-dipolar cycloaddition mechanism (the so-called ketonization reaction) provides a synthetic route for obtaining a new type of carbonyl functionalized polymers and oligomers−unsaturated polyketones.Here, the ketonization of polybutadiene with a relatively high content of trans-1,4-units and 1,2-units at 160−230 °C and elevated pressure was studied. Oxygenated polymer products containing from 0.3 to 8.8 wt % oxygen in the form of carbonyl, mainly ketone, groups and having M n from 34000 to 860 g/mol, respectively, have been obtained. The conversion of ca. 10% of double bonds in the parent polybutadiene during the reaction transforms it into carbonyl functionalized liquid rubber. A comparison of the obtained results with those for ketonization of cis-1,4-polybutadiene has revealed the effect of cis/trans isomerism of 1,4-units and the content of 1,2-units on the reaction mechanism and the characteristics of the resulting polymer products.

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“…The reaction products are benzoquinoneimines and nitroxyl radicals. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In 1969, the mechanism of the antioxidant action of secondary aromatic amines Ar 2 NH through Ar 2 NO • radicals was proposed. [18] Its differences at low and high temperatures were discovered a few years later.…”

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confidence: 99%

Quantum‐chemical studies of the antioxidant effectiveness of para‐phenylene diamines

Breza

Jelemenská

2022

Vinyl Additive Technology

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The purpose of this review is to highlight how the antioxidant effectiveness (AE) of rubber additives can be quantitatively interpreted using results from quantum‐chemical calculations. The relationships between the AE of para‐phenylene diamines (PPD), evaluated through non‐isothermal differential scanning calorimetry measurements in styrene‐butadiene and polyisoprene rubber matrices, and various parameters obtained by quantum‐chemical calculations are reviewed. The N atom between both phenyl rings (A site) is more significant than the N atom between the phenyl ring and the alkyl chain (B site). The preferred formation of ketimine structures (instead of the quinonediimine ones) during dehydrogenation despite the higher stability of the NA‐centered radicals indicates a kinetic control of the antioxidant action. In most cases, the AE decreases with the strength of the NA–HA bond and increases with the chemical shifts of NA and HA. In hypothetical Cu(II) complexes, the AE rises with the affinity of NA to Cu, and the extent of electron density transfer from NA to Cu. Most deviations from linearity might be explained by steric hindrances. Reverse trends for the NA and NB chemical shifts are observed, despite the fact that similar reactions are supposed at both sites.

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Ozonolysis of Natural Rubber: A Critical Review

Cited by 17 publications

References 60 publications

Ozone and its Reactions with Diene Rubbers

Ozone and its Reactions with Diene Rubbers

The Effect of 1,2- and trans-1,4-Units on Ketonization of Polybutadienes by Nitrous Oxide

Quantum‐chemical studies of the antioxidant effectiveness of para‐phenylene diamines

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