Thermal and thermo-oxidative stability of reprocessed poly(ethylene terephthalate)

J. D. Badia, A. Martinez-Felipe, L. Santonja-Blasco, A. Ribes-Greus

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

An exhaustive assessment of the behaviour of virgin and mechanically reprocessed poly(ethylene terephthalate) (PET) facing thermal and thermo-oxidative decomposition processes is presented in this work, as an approach for the energetic valorisation of post-consumer PET goods. Multi-rate linear-non-isothermal thermogravimetric (TGA) experiments under inert (Ar) and reactive (O2) conditions were performed to virgin PET and its recyclates in order to simulate the thermal behaviour of the materials facing pyrolysis and combustion processes. The release of gases was monitored by evolved gas analysis of the fumes of the TGA experiment, by in-line Fourier-transform infrared (IR) analysis, with the aid of 2D-correlation IR characterisation. A kinetic analysis methodology, consisting in the combination of six different methods (namely Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Vyazovkin, Master-Curves and Perez-Maqueda criterion along with Coats–Redfern equation) was applied. Its validity for being used for both constant and variable kinetic parameters was discussed. The kinetic model that described both thermal and thermo-oxidative decompositions of PET and its recyclates was of the type An: nucleation and growth of gas bubbles in the melt. Novel parameters and functions were proposed to characterise the thermal stability along the reprocessing cycles, as well as the variation of the activation energy and the pre-exponential factor during thermal and thermo-oxidative decompositions. The reliability of a simplified kinetic triplet with constant activation parameters was suitable only under thermal decomposition. The usability of PET after reprocessing showed a threshold in the thermal performance from the second recyclate on. During thermal and thermo-oxidative processes, reprocessed PET behaved similarly to virgin PET, and thus current energetic valorisation technologies could be assimilable for all materials.
Original languageEnglish
Pages (from-to)191-202
Number of pages12
JournalJournal of Analytical and Applied Pyrolysis
Volume99
Early online date15 Oct 2012
DOIs
Publication statusPublished - Jan 2013

Fingerprint

Polyethylene Terephthalates
Polyethylene terephthalates
Decomposition
Kinetics
Pyrolysis
Gases
Infrared radiation
Fumes
Gas fuel analysis
Kinetic parameters
Hot Temperature
Fourier transforms
Thermodynamic stability
Nucleation
Activation energy
Experiments
Chemical activation

Keywords

  • Poly(ethylene terephthalate) (PET)
  • Thermal decomposition
  • Thermo-oxidative decomposition
  • Thermogravimetry (TGA)
  • Evolved-gas analysis (EGA)
  • 2D-correlation infrared analysis (2D-IR)
  • Kinetic analysis

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)

Cite this

Thermal and thermo-oxidative stability of reprocessed poly(ethylene terephthalate). / Badia, J. D.; Martinez-Felipe, A.; Santonja-Blasco, L.; Ribes-Greus, A.

In: Journal of Analytical and Applied Pyrolysis , Vol. 99, 01.2013, p. 191-202.

Research output: Contribution to journalArticle

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AB - An exhaustive assessment of the behaviour of virgin and mechanically reprocessed poly(ethylene terephthalate) (PET) facing thermal and thermo-oxidative decomposition processes is presented in this work, as an approach for the energetic valorisation of post-consumer PET goods. Multi-rate linear-non-isothermal thermogravimetric (TGA) experiments under inert (Ar) and reactive (O2) conditions were performed to virgin PET and its recyclates in order to simulate the thermal behaviour of the materials facing pyrolysis and combustion processes. The release of gases was monitored by evolved gas analysis of the fumes of the TGA experiment, by in-line Fourier-transform infrared (IR) analysis, with the aid of 2D-correlation IR characterisation. A kinetic analysis methodology, consisting in the combination of six different methods (namely Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Vyazovkin, Master-Curves and Perez-Maqueda criterion along with Coats–Redfern equation) was applied. Its validity for being used for both constant and variable kinetic parameters was discussed. The kinetic model that described both thermal and thermo-oxidative decompositions of PET and its recyclates was of the type An: nucleation and growth of gas bubbles in the melt. Novel parameters and functions were proposed to characterise the thermal stability along the reprocessing cycles, as well as the variation of the activation energy and the pre-exponential factor during thermal and thermo-oxidative decompositions. The reliability of a simplified kinetic triplet with constant activation parameters was suitable only under thermal decomposition. The usability of PET after reprocessing showed a threshold in the thermal performance from the second recyclate on. During thermal and thermo-oxidative processes, reprocessed PET behaved similarly to virgin PET, and thus current energetic valorisation technologies could be assimilable for all materials.

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KW - 2D-correlation infrared analysis (2D-IR)

KW - Kinetic analysis

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JO - Journal of Analytical and Applied Pyrolysis

JF - Journal of Analytical and Applied Pyrolysis

SN - 0165-2370

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