Zum Mechanismus der thermischen Abspaltung von Chlorwasserstoff aus Polyvinylchlorid. 9. mitt.: Zur struktur der verzweigungen in polyvinylchlorid

Braun, Von Dietrich; Weiss, Frank

doi:10.1002/apmc.1970.050130105

Cited by 21 publications

(1 citation statement)

References 19 publications

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“…In PVC macromolecules the amount of double bonds is about 1.6 per 1000 monomer units. 3 Geddes4 found the average length of polyenes in degraded PVC to be 10-15 by comparing the quantity of evolved HCI with the number of formed polyenes which was determined by ozonolysis. On the basis of electron absorption spectra of decomposed PVC, Braun and Thallmaier5 have shown that the average length of conjugated double bonds is equal to 5-10. There are many unsettled questions concerning the mechanism of the thermal degradation of PVC.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the thermal degradation of poly(vinyl chloride)

Troitskii¹,

Troitskaya²,

Myakov³

et al. 1973

J. polym. sci., C Polym. symp.

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SYNOPSISThe kinetics for dehydrochlorination and benzene formation has been studied during the degradation of two samples of poly(viny1 chloride) (PVC) at 180-200°C under vacuum with and without the removal of hydrogen chloride. The effects of various additives, such as organic phosphites, mercury, silver, gold, and glass upon the thermal degradation of PVC were investigated. Mercury, silver, and glass decrease the rate of autocatalytic dehydrochlorination of the polymer in the presence of hydrogen chloride but silver and glass do not affect PVC degradation rate in the absence of HCI. PVC thermal decomposition under vacuum with removal of HCI mostly proceeds by a molecular mechanism. At the same time, radical reactions take place. But there are some very endothermic stages of chain propagation, this is why in this case, the radical mechanism of PVC dehydrochlorination does not compete with the molecular one. In the presence of HCI, the rate of radical reactions increases and predominates over rate of molecular reactions.

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Section: Introductionmentioning

confidence: 99%

Mechanism of the thermal degradation of poly(vinyl chloride)

Troitskii¹,

Troitskaya²,

Myakov³

et al. 1973

J. polym. sci., C Polym. symp.

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On the thermal degradation of poly(vinyl chloride). Synergistic effect of mixtures of lead and zinc carboxylates

Odilora¹

1989

Acta Polymerica

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The effect of a mixture of lead and zinc carboxylates on the thermal decomposition of poly(vinyl chloride) in air is studied. The results obtained by weight loss determination and IR and UV spectroscopic analysis showed a marked influence of these compounds on the degradation of PVC. The greatest stabilization was achieved with lead dodecanoate. With a mixture of lead octadecanoate and zinc octadecanoate an indication of synergism was observed leading to enhanced stabilization. With the mixture of lead and zinc dodecanoate the level of stabilization was less; this mixture catalysed the degradation of PVC at 473 K. The mechanism of the stabilization of PVC by the studied compounds is discussed.

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Zum Mechanismus der thermischen Abspaltung von Chlorwasserstoff aus Polyvinylchlorid. 10. Mitt.:. Bestimmung des doppelbindungsgehaltes in polyvinylchlorid durch oxydative kettenspaltung

Braun

Quarg

1973

Angew. Makromol. Chem.

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ZUSAMMENFASSUNG :Zur Bestimmung von ungesiittigten Strukturen innerhalb der PolyvinylchloridMakromolekule eignet sich die Oxidation mit Kaliumpermanganat. Bei der Spaltung der Doppelbindungen in den Polyvinylchloridketten mit Kaliumpermanganat tzitt eine merkliche Erniedrigung des Molekulargewichts der Polymeren ein.Reaktionsverlauf und Temperaturabhiingigkeit der Reaktion werden in N.N-Dimethylacetamid als Losungsmittel untersucht. Die Aktivierungsenergie der Oxidationsreaktion ergibt sich aus der Temperaturabhiingigkeit zu 23,9 kcal/Mol. Der Vergleich der Molekulargewichte der untersuchten Polyvinylchloride vor und nach der Oxidation liefert ein Ma13 fur den Doppelbindungsgehalt der Proben. Fur die meisten untersuchten Polymeren wurden Gehalte von 0,2 bis 1,2 kettenstiindigen Doppelbindungen pro 1 000 Kohlenstoff-Atome gefunden. SUMMARY:For determination of random unsaturation within the macromolecules of polyvinyl chloride the oxidation of double bonds by potassium pennanganate is used. After the cleavage of the polymer with potassium pennanganate a remarkable decrease in molecular weight is observed.The oxidation reaction was investigated using N.N-dimethylacetamide as a solvent. From the temperature dependence of the reaction rate an activation energy of 23,9 kaal/mole is calculated. A comparison of the molecular weights before and after oxidation gives the average content of double bonds within different samples, which was found for the products under investigation from 0.2 to 1.2 double bonds per 1000 carbon atoms by this method.

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Zum Mechanismus der thermischen Abspaltung von Chlorwasserstoff aus Polyvinylchlorid. 9. mitt.: Zur struktur der verzweigungen in polyvinylchlorid

Cited by 21 publications

References 19 publications

Mechanism of the thermal degradation of poly(vinyl chloride)

Mechanism of the thermal degradation of poly(vinyl chloride)

On the thermal degradation of poly(vinyl chloride). Synergistic effect of mixtures of lead and zinc carboxylates

Zum Mechanismus der thermischen Abspaltung von Chlorwasserstoff aus Polyvinylchlorid. 10. Mitt.:. Bestimmung des doppelbindungsgehaltes in polyvinylchlorid durch oxydative kettenspaltung

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