Formation of anomalous structures in PVC and their influence on the thermal stability: 3. Internal chloroallylic groups

Hjertberg, Thomas; Sörvik, Erling M.

doi:10.1016/0032-3861(83)90004-6

Cited by 72 publications

(36 citation statements)

References 29 publications

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“…51 According to Ravey et al 52 the polymer-rich phase is (2), and the propagation (3) reactions of the model vinyl chloride propagating radical (4). Also shown are the geometries of the corresponding vinyl chloride "polymer" (5), the radical product (6) of the 1-2 hydrogen shifts, vinyl chloride monomer (7), chloroallylic end group (8), and the addition of the propagating PVC radical to the double bond of the chloroallylic end group (9). much less swollen in the monomer at conversions higher than 85%.…”

Section: Scheme 8 Model Reactions Used In the Calculation Of The Ratmentioning

confidence: 99%

New Insight into the Formation of Structural Defects in Poly(Vinyl Chloride)

et al. 2005

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The monomer conversion dependence of the formation of the various types of defect structures in radical suspension polymerization of vinyl chloride was examined via both 1H and 13C NMR spectrometry. The rate coefficients for model propagation and intra- and intermolecular hydrogen abstraction reactions were obtained via high-level ab initio molecular orbital calculations. An enormous increase in the formation of both branched and internal unsaturated structures was observed at conversions above 85%, and this is mirrored by a sudden decrease in stability of the resulting PVC polymer. Above this threshold-conversion, the monomer is depleted from the polymer-rich phase, and the propagation rate is thus substantially reduced, thereby allowing the chain-transfer processes to compete more effectively. In contrast to the other defects, the chloroallylic end groups were found to decrease at high conversions. On the basis of the theoretical and experimental data obtained in this study, this decrease was attributed to copolymerization and abstraction reactions that are expected to be favored at high monomer conversions. Finally, a surprising increase in the concentration of the methyl branches was reported. Although a definitive explanation for this behavior is yet to be obtained, the involvement of transfer reactions of an intra- or intermolecular nature seems likely, and (in the latter case) these could lead to the presence of tertiary chlorine in these defects.

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Section: Scheme 8 Model Reactions Used In the Calculation Of The Ratmentioning

confidence: 99%

New Insight into the Formation of Structural Defects in Poly(Vinyl Chloride)

et al. 2005

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“…This is distinguished from the thermal activation of the unirradiated PVC in which the tertiary sites have been found to play a more important role than allylic chlorine structures. 30 In the case of the in situ irradiation, the ultimate effect is governed by at least two factors. One is due to the temperature dependence of G(HCl), and the other is due to the dose dependence of dehydrochlorination and allylic chlorine structure formation.…”

Section: Discussionmentioning

confidence: 99%

Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Zhao

Yamamoto

Tagawa

1998

J. Polym. Sci. A Polym. Chem.

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Radiation effects on the formation of conjugated double bonds in the thermal degradation of poly(vinyl chloride) (PVC) and poly(vinyl alcohol) (PVA) were investigated. Thin films of PVC and PVA were either irradiated with γ‐rays at ambient temperature (pre‐irradiation) and then subjected to thermal treatment, or irradiated at elevated temperatures (in situ irradiation). An extensive enhancement of the thermal degradation was observed for the pre‐irradiation of the PVC films, which was more effective than the effect of the in situ irradiation at the same absorption dose. For the PVA degradation, however, the effect of the in situ irradiation was larger than that of the pre‐irradiation. The results were explained and related mechanisms were discussed based on radiation‐induced chemical reactions and their individual contributions to the thermal degradation behaviors of the two polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3089–3095, 1998

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“…3,4,9,23,[25][26][27][29][30][31][32][33]42,43 The main goal of these investigations was to determine how and to what extent structural defects in PVC are formed.…”

Section: Structural Defects Contentmentioning

confidence: 99%

Microkinetic Modeling of Structural Properties of Poly(vinyl chloride)

2009

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The free radical suspension polymerization of vinyl chloride is modeled at the elementary reaction level, systematically taking into account diffusion limitations. By deriving balances for structurally distinct polymer and radical species the formation of structural defects can be followed: monomer conversion, averages of the molar mass distribution and the structural defects content can be calculated as a function of polymerization time for industrially relevant conditions. A good agreement between literature reported and calculated values for these properties is obtained for a polymerization temperature range of 325-340 K, a dicetyl peroxydicarbonate and dimyristyl peroxydicarbonate initiator concentration range of 0.00069-1.0 wt %, and a monomer conversion range of 12-96%. The increase of the branching content and the decrease of the terminal double bond content at high monomer conversions can be explained in terms of a favoring of monomolecular reactions and the increasing importance of addition reactions to unsaturations at these conditions.

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Formation of anomalous structures in PVC and their influence on the thermal stability: 3. Internal chloroallylic groups

Cited by 72 publications

References 29 publications

New Insight into the Formation of Structural Defects in Poly(Vinyl Chloride)

New Insight into the Formation of Structural Defects in Poly(Vinyl Chloride)

Radiation effects on the thermal degradation of poly(vinyl chloride) and poly(vinyl alcohol)

Microkinetic Modeling of Structural Properties of Poly(vinyl chloride)

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