Chain extension of poly(ethylene terephthalate) by reactive blending using diepoxides

• Published in: Journal of applied polymer science Vol. 71; no. 13; pp. 2121 - 2127
• Main Authors: Haralabakopoulos, A. A., Tsiourvas, D., Paleos, C. M.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 28.03.1999; Wiley
• Subjects: Applied sciences; chain extension; Chemical modifications; Chemical reactions and properties; diepoxides; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; poly(ethylene terephthalate); reactive blending; Diepoxide; Ethylene terephthalate polymer; Structure processing relationship; Molten state; Liquid liquid reaction; Chain elongation; Experimental study; Property processing relationship; Melting point; Glass transition temperature
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/(SICI)1097-4628(19990328)71:13<2121::AID-APP1>3.0.CO;2-Y

Molecular weight increase via chain extension reactions of poly(ethylene terephthalate) with commercially available diepoxides was studied in a custom‐made laboratory scale reactor and a Brabender rheomixer under reactive blending conditions. The products were characterized by carboxylic end group analysis, intrinsic viscosity, and differential scanning calorimetry. PET was effectively modified in the laboratory‐scale reactor using cyclic diepoxides because the resulting polymers show intrinsic viscosities that are comparable to virgin PET (0.68–0.75 dL/g vs. 0.74 dL/g) and much higher than processed PET (0.55), while carboxyl contents were reduced to a third of that of the virgin PET. Diglycidyl ethers produced polymers displaying decreased viscosity values, increased carboxyl content, and lower melting points. Low concentrations of extender and short reaction times generally favored chain extension. In addition, purging with nitrogen resulted in chain extended polymers having the highest values of intrinsic viscosity ([η] = 0.79, 0.82). Similar trends were observed with modified products in the rheomixer having somewhat smaller viscosity values, larger carboxyl contents, and increased melting points. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2121–2127, 1999