Thermal properties, degradation and stability of poly(vinyl chloride) predegraded thermooxidatively in the presence of dioctyl phthalate plasticizer

Györgyi Szarka, B. Iván

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10 Citations (Scopus)

Abstract

Thermooxidative degradation of poly(vinyl chloride) (PVC) is inevitable during its processing. Recycling of this polymer requires reprocessing in most cases, and due to the low thermal stability of PVC, it is of paramount importance to reveal the effect of thermooxidation on the thermal stability of this commercially important polymer. However, detailed systematic investigations are lacking on this crucial problem. In this study, the thermal behavior of PVCs thermooxidized in dilute dioctyl phthalate (DOP) (di(2-ethylhexyl) phthalate, DEHP) plasticizer was investigated by DSC, thermal gravimetry and isothermal degradation under inert atmosphere. It was found that thermooxidation leads to PVCs with certain extent of internal plasticization by DOP chemically bound to the PVC chains and by the oxidized chain segments as well. Thermogravimetry and isothermal dehydrochlorination under inert atmosphere revealed that even low extent of thermooxidation of PVC (0.4 mol% of HCl loss in 30 min at 200°C) leads to dramatically decreased thermal stability of this polymer with 50-60°C lower onset decomposition temperature than that of the virgin resin. This unexpected finding means that at least part of the oxidized moieties formed during oxidation of the PVC chains acts as initiators for thermal dehydrochlorination at relatively low temperatures, resulting in significant decrease of the thermal stability of the polymer. These striking results also indicate that the decreased thermal stability caused by thermooxidation in the course of the primary processing of this polymer should be taken into account in order to efficiently stabilize PVC products for reprocessing and recycling.

Original languageEnglish
Pages (from-to)208-214
Number of pages7
JournalJournal of Macromolecular Science - Pure and Applied Chemistry
Volume50
Issue number2
DOIs
Publication statusPublished - Jan 1 2013

Fingerprint

Diethylhexyl Phthalate
Vinyl Chloride
Plasticizers
Polyvinyl Chloride
Polyvinyl chlorides
Thermodynamic properties
Degradation
Thermooxidation
Polymers
Thermodynamic stability
Recycling
Gravimetric analysis
Processing
Thermogravimetric analysis
Resins
Decomposition
Oxidation
Temperature

Keywords

  • chain scission
  • degradation
  • dioctyl phthalate
  • plasticizer
  • PVC
  • recycling
  • thermal stability
  • thermooxidation

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics
  • Ceramics and Composites
  • Chemistry(all)

Cite this

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title = "Thermal properties, degradation and stability of poly(vinyl chloride) predegraded thermooxidatively in the presence of dioctyl phthalate plasticizer",
abstract = "Thermooxidative degradation of poly(vinyl chloride) (PVC) is inevitable during its processing. Recycling of this polymer requires reprocessing in most cases, and due to the low thermal stability of PVC, it is of paramount importance to reveal the effect of thermooxidation on the thermal stability of this commercially important polymer. However, detailed systematic investigations are lacking on this crucial problem. In this study, the thermal behavior of PVCs thermooxidized in dilute dioctyl phthalate (DOP) (di(2-ethylhexyl) phthalate, DEHP) plasticizer was investigated by DSC, thermal gravimetry and isothermal degradation under inert atmosphere. It was found that thermooxidation leads to PVCs with certain extent of internal plasticization by DOP chemically bound to the PVC chains and by the oxidized chain segments as well. Thermogravimetry and isothermal dehydrochlorination under inert atmosphere revealed that even low extent of thermooxidation of PVC (0.4 mol{\%} of HCl loss in 30 min at 200°C) leads to dramatically decreased thermal stability of this polymer with 50-60°C lower onset decomposition temperature than that of the virgin resin. This unexpected finding means that at least part of the oxidized moieties formed during oxidation of the PVC chains acts as initiators for thermal dehydrochlorination at relatively low temperatures, resulting in significant decrease of the thermal stability of the polymer. These striking results also indicate that the decreased thermal stability caused by thermooxidation in the course of the primary processing of this polymer should be taken into account in order to efficiently stabilize PVC products for reprocessing and recycling.",
keywords = "chain scission, degradation, dioctyl phthalate, plasticizer, PVC, recycling, thermal stability, thermooxidation",
author = "Gy{\"o}rgyi Szarka and B. Iv{\'a}n",
year = "2013",
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T1 - Thermal properties, degradation and stability of poly(vinyl chloride) predegraded thermooxidatively in the presence of dioctyl phthalate plasticizer

AU - Szarka, Györgyi

AU - Iván, B.

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N2 - Thermooxidative degradation of poly(vinyl chloride) (PVC) is inevitable during its processing. Recycling of this polymer requires reprocessing in most cases, and due to the low thermal stability of PVC, it is of paramount importance to reveal the effect of thermooxidation on the thermal stability of this commercially important polymer. However, detailed systematic investigations are lacking on this crucial problem. In this study, the thermal behavior of PVCs thermooxidized in dilute dioctyl phthalate (DOP) (di(2-ethylhexyl) phthalate, DEHP) plasticizer was investigated by DSC, thermal gravimetry and isothermal degradation under inert atmosphere. It was found that thermooxidation leads to PVCs with certain extent of internal plasticization by DOP chemically bound to the PVC chains and by the oxidized chain segments as well. Thermogravimetry and isothermal dehydrochlorination under inert atmosphere revealed that even low extent of thermooxidation of PVC (0.4 mol% of HCl loss in 30 min at 200°C) leads to dramatically decreased thermal stability of this polymer with 50-60°C lower onset decomposition temperature than that of the virgin resin. This unexpected finding means that at least part of the oxidized moieties formed during oxidation of the PVC chains acts as initiators for thermal dehydrochlorination at relatively low temperatures, resulting in significant decrease of the thermal stability of the polymer. These striking results also indicate that the decreased thermal stability caused by thermooxidation in the course of the primary processing of this polymer should be taken into account in order to efficiently stabilize PVC products for reprocessing and recycling.

AB - Thermooxidative degradation of poly(vinyl chloride) (PVC) is inevitable during its processing. Recycling of this polymer requires reprocessing in most cases, and due to the low thermal stability of PVC, it is of paramount importance to reveal the effect of thermooxidation on the thermal stability of this commercially important polymer. However, detailed systematic investigations are lacking on this crucial problem. In this study, the thermal behavior of PVCs thermooxidized in dilute dioctyl phthalate (DOP) (di(2-ethylhexyl) phthalate, DEHP) plasticizer was investigated by DSC, thermal gravimetry and isothermal degradation under inert atmosphere. It was found that thermooxidation leads to PVCs with certain extent of internal plasticization by DOP chemically bound to the PVC chains and by the oxidized chain segments as well. Thermogravimetry and isothermal dehydrochlorination under inert atmosphere revealed that even low extent of thermooxidation of PVC (0.4 mol% of HCl loss in 30 min at 200°C) leads to dramatically decreased thermal stability of this polymer with 50-60°C lower onset decomposition temperature than that of the virgin resin. This unexpected finding means that at least part of the oxidized moieties formed during oxidation of the PVC chains acts as initiators for thermal dehydrochlorination at relatively low temperatures, resulting in significant decrease of the thermal stability of the polymer. These striking results also indicate that the decreased thermal stability caused by thermooxidation in the course of the primary processing of this polymer should be taken into account in order to efficiently stabilize PVC products for reprocessing and recycling.

KW - chain scission

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