Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods
Polyethylene terephthalate (PET) films are used when mechanical strength, thermal and chemical stability, and barrier properties to atmospheric gases are required in combination with good processability. Hydrolysis leading to embrittlement of the material is a major concern as PET is used in a varie...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2023-08-01
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| Series: | Polymer Testing |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0142941823002106 |
| _version_ | 1797774848390332416 |
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| author | Gernot Oreski Bettina Ottersböck Chiara Barretta Petra Christöfl Simone Radl Gerald Pinter |
| author_facet | Gernot Oreski Bettina Ottersböck Chiara Barretta Petra Christöfl Simone Radl Gerald Pinter |
| author_sort | Gernot Oreski |
| collection | DOAJ |
| description | Polyethylene terephthalate (PET) films are used when mechanical strength, thermal and chemical stability, and barrier properties to atmospheric gases are required in combination with good processability. Hydrolysis leading to embrittlement of the material is a major concern as PET is used in a variety of applications with expected lifetimes of up to decades (e.g., for use in buildings, textiles, or photovoltaic backsheets). Therefore, a comprehensive understanding of the degradation processes and the effects on the molecular mass distribution is of great importance.Usually, the direct determination of molar mass and molar mass distribution involves high effort and sophisticated equipment. Therefore, the main objective of this work is to quantify molar mass changes due to accelerated aging using thermal and mechanical methods. Two stabilized PET films were subjected to seven different accelerated aging conditions (heat; combined heat-humidity). The samples were then characterized by size exclusion chromatography (SEC), tensile tests and differential scanning calorimetry (DSC).A linear correlation was found between crystallization temperature and average molar mass. The values of fracture stress from tensile tests indicate a ductile-brittle transition at a molar mass of 15 000 g mol−1. The study concludes that the crystallization temperature obtained from DSC measurements can be used to estimate changes in the average molar mass of PET after hydrolysis. Crystallization temperatures between 208 °C and 211 °C correspond to a critical reduction in molar mass and severe embrittlement. |
| first_indexed | 2024-03-12T22:27:11Z |
| format | Article |
| id | doaj.art-e2f1f3c6aced43cc86b2ca0ceaa601b0 |
| institution | Directory Open Access Journal |
| issn | 0142-9418 |
| language | English |
| last_indexed | 2024-03-12T22:27:11Z |
| publishDate | 2023-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Polymer Testing |
| spelling | doaj.art-e2f1f3c6aced43cc86b2ca0ceaa601b02023-07-22T04:51:11ZengElsevierPolymer Testing0142-94182023-08-01125108130Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methodsGernot Oreski0Bettina Ottersböck1Chiara Barretta2Petra Christöfl3Simone Radl4Gerald Pinter5Polymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700, Leoben, Austria; University of Leoben, Department of Material Science and Testing of Polymers, Leoben, Austria; Corresponding author. Polymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700, Leoben, Austria.Polymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700, Leoben, AustriaPolymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700, Leoben, AustriaPolymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700, Leoben, AustriaPolymer Competence Center Leoben GmbH, Roseggerstraße 12, 8700, Leoben, AustriaUniversity of Leoben, Department of Material Science and Testing of Polymers, Leoben, AustriaPolyethylene terephthalate (PET) films are used when mechanical strength, thermal and chemical stability, and barrier properties to atmospheric gases are required in combination with good processability. Hydrolysis leading to embrittlement of the material is a major concern as PET is used in a variety of applications with expected lifetimes of up to decades (e.g., for use in buildings, textiles, or photovoltaic backsheets). Therefore, a comprehensive understanding of the degradation processes and the effects on the molecular mass distribution is of great importance.Usually, the direct determination of molar mass and molar mass distribution involves high effort and sophisticated equipment. Therefore, the main objective of this work is to quantify molar mass changes due to accelerated aging using thermal and mechanical methods. Two stabilized PET films were subjected to seven different accelerated aging conditions (heat; combined heat-humidity). The samples were then characterized by size exclusion chromatography (SEC), tensile tests and differential scanning calorimetry (DSC).A linear correlation was found between crystallization temperature and average molar mass. The values of fracture stress from tensile tests indicate a ductile-brittle transition at a molar mass of 15 000 g mol−1. The study concludes that the crystallization temperature obtained from DSC measurements can be used to estimate changes in the average molar mass of PET after hydrolysis. Crystallization temperatures between 208 °C and 211 °C correspond to a critical reduction in molar mass and severe embrittlement.http://www.sciencedirect.com/science/article/pii/S0142941823002106PETHydrolysisMolar mass estimationCritical molar massDSCDegradation |
| spellingShingle | Gernot Oreski Bettina Ottersböck Chiara Barretta Petra Christöfl Simone Radl Gerald Pinter Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods Polymer Testing PET Hydrolysis Molar mass estimation Critical molar mass DSC Degradation |
| title | Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods |
| title_full | Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods |
| title_fullStr | Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods |
| title_full_unstemmed | Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods |
| title_short | Degradation of PET – Quantitative estimation of changes in molar mass using mechanical and thermal characterization methods |
| title_sort | degradation of pet quantitative estimation of changes in molar mass using mechanical and thermal characterization methods |
| topic | PET Hydrolysis Molar mass estimation Critical molar mass DSC Degradation |
| url | http://www.sciencedirect.com/science/article/pii/S0142941823002106 |
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