Thermo‐rheological analysis of various chain extended recycled poly(ethylene terephthalate)

Three chain extenders, pyromellitic dianhydride (PMDA), ethylene carbonate (EC), and a polymeric‐epoxide, were investigated for improving recycled p(ethylene terephthalate) (r‐PET) properties with melt extrusion. The amount of additives and processing temperatures were also varied to check for melt...

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Bibliographic Details
Published in:Polymer engineering and science 2020-10, Vol.60 (10), p.2511-2516
Main Authors: Pandey, Vivek, Seese, Michael, Maia, João M., Schiraldi, David A.
Format: Article
Language:English
Subjects:
Additives
Carbonates
chain extension
Dianhydrides
Epoxy compounds
Extrusion
Mechanical properties
poly(ethylene terephthalate)
Polyethylene terephthalate
processing
recycle
Rheological properties
Rheology
Rheometry
Shear thinning (liquids)
Thermal properties
Viscosity
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Summary:Three chain extenders, pyromellitic dianhydride (PMDA), ethylene carbonate (EC), and a polymeric‐epoxide, were investigated for improving recycled p(ethylene terephthalate) (r‐PET) properties with melt extrusion. The amount of additives and processing temperatures were also varied to check for melt degradation. Small amplitude oscillatory shear experiments were performed to probe rheological changes with different chain extenders. Capillary rheometry with haul‐off was also performed to measure extensional viscosity and melt strength. Higher loadings of the chain extenders were found to improve properties of r‐PET. These chain extenders definitely increased melt viscosities when incorporated at the higher level of the ranges examined, matching that of virgin PET. EC addition resulted in high shear thinning of the polymer. Epoxy and PMDA added to r‐PET produced products with the same extensional viscosity as v‐PET. Haul‐off experiments demonstrate superior performance by epoxy‐modified r‐PET compared to v‐PET. Three commercially available chain extenders for polyesters are compared for use in PET recycle. An epoxy and pyromellitic dianydride were generally more effective than ethylene carbonate for reactive extrusion chain extension, producing rheological effects useful in downstream processing of the products.
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.25488