Saturated irregular structures in poly(vinyl chloride)

Valko, L.; Tvaroŝka, Igor; Kovařı́k, Pavel

doi:10.1016/0014-3057(75)90025-7

Cited by 25 publications

(6 citation statements)

References 10 publications

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“…The slight increase of PVC degradation activation energies with PVC glass transition temperature indicated that the rates of diffusion of polymer segments may influence the activation energies of initial HCl elimination and HCl autocatalysis of plasticized PVC degradation (Figure 3 , 5, 14). This agreed with the mechanisms of PVC degradation through formation of cyclic transition states as suggested by Wypych, [3,7] Troitskii, [3,16] Valco, [55,56] and Braun. [57] Kinetics parameters of chemical reaction exhibit inherent scatter since several steps are involved in parameters derivation from the experimental data through data processing and model computations.…”

Section: Discussionsupporting

confidence: 90%

“…Valco and coworkers also modeled kinetics of initial HCl elimination from PVC chain. [56] Again, their analysis of four atom transition state requiring PVC chain segments rearrangement would lead to conclusion that activation energy of PVC degradation should be glass transition temperature dependent, as was observed in the present work experimentally (Figure 5). One of the mechanisms of PVC degradation considered by Troitskii and Troitskaya included reactions of polymeric radicals with polymer molecules and formation of ion-biradical species through intramolecular rearrangement not shown or considered here in the overall reaction scheme (Scheme 5).…”

Section: Autocatalysissupporting

confidence: 75%

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Kinetics of Plasticized Poly(vinyl chloride) Thermal Degradation, Induction, Autocatalysis, Glass Transition, Diffusion

Krongauz

2024

ChemistrySelect

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Kinetics of non‐oxidative thermal degradation of poly(vinyl chloride) (PVC) plasticized with di(2‐ethylhexyl)phthalate and epoxidized linseed oil (ELO) were studied using differential scanning calorimetry. PVC thermal degradation autocatalyzed by forming HCl is delayed in the presence of acid scavenging ELO. Direct HCl elimination rates during steady state degradation (induction period) were almost independent on ELO concentration, with rate constants ranging from ≈3.2×10−6 s−1 at 463 K to ≈7.0×10−5 s−1 at 503 K. Activation energy of HCl elimination increased with glass transition temperature (Tg) increase from 136.0 kJ mol−1 at Tg=260.3 K to 141.9 kJ mol−1at Tg=274.2 K. Diffusion coefficients of HCl diffusion in plasticized PVC deduced using Williams‐Landel‐Ferry equation were of the order of 10−4 cm2 sec−1. Calculated activation energy of HCl diffusion in plasticized PVC was ≈30 kJ mol−1. The rate constants of PVC autocatalytic degradation were derived from the experimental data (for the 1st time) using Šesták‐Berggren approach and ranged from 3.2×10−2 sec−1 at 503 K to 4.4×10−3 sec−1 at 463 K. Autocatalysis activation energies ranged from 70.4 kJ mol−1 to 85.1 kJ mol−1 and increased with increase of glass transition temperature. It was established that PVC degradation kinetics was not controlled by HCl diffusion. Compensation effect was observed for initial and catalyzed PVC degradation.

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Section: Discussionsupporting

confidence: 90%

Section: Autocatalysissupporting

confidence: 75%

Kinetics of Plasticized Poly(vinyl chloride) Thermal Degradation, Induction, Autocatalysis, Glass Transition, Diffusion

Krongauz

2024

ChemistrySelect

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“…The only method available for the production of PVC is free-radical polymerization in suspension, emulsion, and bulk. In the absence of additives, PVC is brittle, has a broad molecular weight distribution, contains relatively few intact chain ends, and possesses tertiary chloride and allyl chloride structural defects − that lead to zipperlike dehydrochlorination reactions when the temperature is elevated above T g . To combat these deficiencies, PVC is stabilized with organometallic compounds that are added to inhibit decomposition.…”

Section: Set-dtlrpmentioning

confidence: 99%

Single-Electron Transfer and Single-Electron Transfer Degenerative Chain Transfer Living Radical Polymerization

2009

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Introduction 5069 1.1. Living Radical Polymerization (LRP). Definitions and Brief History 5070 1.2. Scope of the Review 5071 2. Path to SET-LRP and SET-DTLRP: Sulfonyl Halides as "Universal" Initiators for Cu-Catalyzed LRP 5071 2.1. Cuprous Halide Catalysts for LRP Initiated with Sulfonyl Halides 5071 2.2. Cu 0 and Cu 2 O Catalysts for LRP Initiated with Sulfonyl Chlorides 5072 2.3. Arenesulfonyl Bromides, Arenesulfonyl Iodides, and N-Centered Initiators 5073 2.4. TERMINI. The First Iterative Method Based on LRP 5074 3. SET-DTLRP 5075 3.1. Toward the LRP of Vinyl Chloride (VC) 5075 3.1.1. Cu 0 Overcomes the Challenge of Reactivation Required for the Living Radical Polymerization of VC 5075 3.1.2. Cu 0 Catalyzed SET-DTLRP of VC via the Disproportionation of Cu I 5076 3.1.

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“…It has been observed that PVC is more susceptible to dehydrochlorination than its low molecular analogues. The presence of occasional irregularity in the larger molecules, such as head to head configuration (Murayama and Amagi, 1966), allylic chlorine (Suzuki et al, 1971), and branching (tertiary chlorine) (Mayer, 1974;Valko et al, 1975), is considered by many to be an important factor. The chlorine atom at each of these sites could be a site for initiation of dehydrochlorination.…”

Section: Introductionmentioning

confidence: 99%

Role of Metal Oxides in the Thermal Degradation of Poly(vinyl chloride)

Gupta

Viswanath

1998

Ind. Eng. Chem. Res.

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Thermal degradation of poly(vinyl chloride) has been studied in the presence of metal oxides by a thermogravimetric method. It follows a two-step mechanism. In the first step chlorine free radical is formed as in the case of pure PVC, and in the second step chlorine free radical replaces oxygen from metal oxide to form metal chloride and oxygen free radical. Subsequently, the oxygen free radical abstracts hydrogen from PVC. Formation of metal chloride is the rate-controlling step. The metal chlorides formed during the thermal degradation either volatilize or decompose simultaneously to lower metallic chlorides depending on the boiling point or the volatilization temperature.

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Saturated irregular structures in poly(vinyl chloride)

Cited by 25 publications

References 10 publications

Kinetics of Plasticized Poly(vinyl chloride) Thermal Degradation, Induction, Autocatalysis, Glass Transition, Diffusion

Kinetics of Plasticized Poly(vinyl chloride) Thermal Degradation, Induction, Autocatalysis, Glass Transition, Diffusion

Single-Electron Transfer and Single-Electron Transfer Degenerative Chain Transfer Living Radical Polymerization

Role of Metal Oxides in the Thermal Degradation of Poly(vinyl chloride)

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