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Licensed Unlicensed Requires Authentication Published by De Gruyter June 23, 2016

Rheological Characterization and Thermal Stability of Different Intrinsic Viscosity Poly(ethylene terephthalate) in Air and Nitrogen

S.-C. Chen, X.-M. Zhang, M. Liu, J.-P. Ma, W.-Y. Lu and W.-X. Chen


Four PET samples of different intrinsic viscosity values based on diverse manufacturing processes were characterized for their linear viscoelasticity using a parallel plate rheometer. Thermal stability and frequency sweep experiments were performed in the melt state at 270 °C. The influences of drying temperature, testing atmosphere (air or nitrogen), and preparation (granules vs. samples cut from compression molded sheets) were investigated. Results indicated that a higher drying temperature promoted complex viscosity significantly and compression molded sheets generated irreversible structural changes in harsh conditions. The samples measured in air decreased because of thermo-oxidation degradation, whereas that in nitrogen unexpectedly increased slightly because of polycondensation without surface renewal. The role of carboxyl end group towards PET thermal stability was found to be influenced by the atmosphere.

*Correspondence address, Mail address: Wen-Xing Chen, National Engineering Laboratory for Textile Fiber Materials and Processing Technology (Zhejiang), Zhejiang Sci-Tech University, Hangzhou 310018, PRC. E-mail:


Assadi, R., Colin, X. and Verdu, J., “Irreversible Structural Changes during PET Recycling by Extrusion”, Polymer, 45, 44034412 (2004) 10.1016/j.polymer.2004.04.029Search in Google Scholar

Awaja, F., Daver, F. and Kosior, E, “Recycled Poly(ethylene terephthalate) Chain Extension by a Reactive Extrusion Process”, Polym. Eng. Sci., 8, 15791587 (2004) 10.1002/pen.20155Search in Google Scholar

Bikiars, D. N., Karayannidis, N. G., “Effect of Carboxylic End Groups on Thermooxidative Stability of PET and PBT”, Polym. Degrad. Stab., 63, 213218 (1999) 10.1016/S0141-3910(98)00094-9Search in Google Scholar

Bledzki, A. K., OmarF., “Creep and Impact Properties of Wood Fibre-Polypropylene Composites: Influence of Temperature and Moisture Content”, Compos. Sci. Technol., 64, 693700 (2004) 10.1016/S0266-3538(03)00291-4Search in Google Scholar

Cavalcanti, F. N., Teófilo, E. T., Rabello, M. S. and Silva, S. M. L., “Chain Extension and Degradation during Reactive Processing of PET in the Presence of Triphenyl Phosphite”, Polym. Eng. Sci., 12, 21552163 (2007) 10.1002/pen.20912Search in Google Scholar

Chen, W., Ma, J., Wang, J., Hu, Z. and Gao, L., “Research of Liquid-State Polycondensation Technology for Polyester Industrial Yarn”, China Synthetic Fiber Ind., 36, 14 (2013)Search in Google Scholar

Chen, W., PCT/CN2013/082375 (2013)Search in Google Scholar

Ciolacu, C. F. L., Choudhury, N. R. and Dutta, N. K., “Colour Formation in Poly(et hylene terephthalate) during Melt Processing”, Polym. Degrad. Stab., 91, 875885 (2006) 10.1016/j.polymdegradstab.2005.06.021Search in Google Scholar

Davera, F., Guptab, R. and Kosiorc, E.Rheological Characterisation of Recycled Poly(ethylene terephthalate) Modified by Reactive Extrusion”, J. Mater. Process. Tech., 204, 397402 (2008) 10.1016/j.jmatprotec.2007.11.090Search in Google Scholar

Debruin, B. R., U.S. Patent 6 906 164 B2 (2005)Search in Google Scholar

Dhavalikar, R., Yamaguchi, M. and Xanthos, M., “Molecular and Structural Analysis of a Triepoxide-Modified Poly(ethylene terephthalate) from Rheological Data”, J. Polym. Sci. Pol. Chem., 7, 958969 (2003) 10.1002/pola.10641Search in Google Scholar

Härth, M., Kaschta, J. and Schubert, D. W., “Shear and Elongational Flow Properties of Long-Chain Branched Poly(ethylene terephthalates) and Correlations to their Molecular Structure”, Macromolecules, 47, 44714478 (2014) 10.1021/ma5002657Search in Google Scholar

Hatzikiriakos, S. G., Heffner, G., Vlassopoulos, D. and Christodoulou, K., “Rheological Characterization of Poly(ethylene terephthalate) Resins Using a Multimode Phan-Tien-Tanner Constitutive Relation”, Rheol. Acta, 36, 568578 (1997) 10.1007/BF00368134Search in Google Scholar

Herron, D. J., U. S. Patent 4161578 (1979)Search in Google Scholar

IdageB. B., Mahajan, S. S., Sivaram, S., U. S. Patent 5 714 567 (1998)Search in Google Scholar

Kang, C. K., “Modeling of Solid-State Polymerization of Poly(ethylene terephthalate)”, J. Appl. Polym. Sci., 5, 837846 (1998) 10.1002/(SICI)1097-4628(19980502)68:5<837::AID-APP15>3.0.CO;2-NSearch in Google Scholar

Kruse, M., Rolón-Garrido, V. H. and Wagner, M. H., “Rheological Characterization of Degradation and Polycondensation of Poly-(ethylene terephthalate) Melt in Air and in Nitrogen”, AIP Conf. Proc. Papers, 216–229 (2013) 10.1063/1.4802616Search in Google Scholar

Ma, Y., Agarwal, U. S, “Solvent Assisted Post-Polymerization of PET”, Polymer, 46, 54475455 (2005) 10.1016/j.polymer.2005.05.003Search in Google Scholar

Montaudo, G., Puglisi, C. and Samperi, F., “Primary Thermal Degradation Mechanisms of PET and PBT”, Polym. Degrad. Stab., 42, 1328 (1993) 10.1016/0141-3910(93)90021-ASearch in Google Scholar

Nguyen, Q. T., Japon, S., Luciani, A., Leterrier, Y. and Månson, J. A. E., “Molecular Characterization and Rheological Properties of Modified Poly(ethylene terephthalate) Obtained by Reactive Extrusion”, Polym. Eng. Sci., 8, 12991309 (2001) 10.1002/pen.10830Search in Google Scholar

Pang, K., Kotek, R. and Tonelli, A., “Review of Conventional and Novel Polymerization Processes for Polyesters”, Prog. Polym. Sci., 31, 10091037 (2006) 10.1016/j.progpolymsci.2006.08.008Search in Google Scholar

Ren, J., Krishnamoorti, R., “Nonlinear Viscoelastic Properties of Layered-Silicate-Based Intercalated Nanocomposites”, Macromolecules, 36, 44434451 (2003) 10.1021/ma020412nSearch in Google Scholar

Romão, W., Franco, M. F., Corilo, Y. E., Eberlin, M. N., Spinacé, M. A. S. and Paoli, M. A. D., “Poly(ethylene terephthalate) Thermo-Mechanical and Thermo-Oxidative Degradation Mechanisms”, Polym. Degrad. Stab., 94, 18491859 (2009) 10.1016/j.polymdegradstab.2009.05.017Search in Google Scholar

Rosu, R. F., Shanks, R. A. and Bhattacharya, S. N., “Shear Rheology and Thermal Properties of Linear and Branched Poly(ethylene terephthalate) Blends”, Polymer, 40, 58915898 (1999) 10.1016/S0032-3861(98)00814-3Search in Google Scholar

Samperia, F., Puglisia, C., Alicatab, R. and Montaudob, G., “Thermal Degradation of Poly(ethylene terephthalate) at the Processing Temperature”, Polym. Degrad. Stab., 83, 310 (2004) 10.1016/S0141-3910(03)00166-6Search in Google Scholar

Scheirs, J., Long, T. E. (Eds.), “Modern Polyesters: Chemistry and Technology of Polyesters and Copolymers”, John Wiley & Sons Ltd., West Sussex, UK (2003)10.1002/0470090685Search in Google Scholar

Seo, K. S., Cloyd, J. D., “Kinetics of Hydrolysis and Thermal Degradation of Polyester Melts”. J. Appl. Polym. Sci., 42, 845850 (1991) 10.1002/app.1991.070420330Search in Google Scholar

Shaw, G., Schaller, R. A., Stikeleather, W. J., Melton, M. D., Hey, H., Schmidt, R., Hartmann, R. and Lohe, H., U. S. Patent 5599507 (1997)Search in Google Scholar

Tseng, T. C., Hanan, J. C., “Rheological Characterization of Poly-(ethylene terephthalate) Resins Used in the Bottling Industry”, SPE ANTEC Tech. Papers, 2292–2295 (2011)Search in Google Scholar

Utracki, L. A., Catani, A. M., Bata, G. L., Kamal, M. R. and Tam, V., “Melt Rheology of Blends of Semicrystalline Polymers. I. Degradation and Viscosity of Poly(ethylene terephthalate)-Polyamide-6,6 Mixtures”, J. Appl. Polym. Sci., 27, 19131931 (1982) 10.1002/app.1982.070270606Search in Google Scholar

Vouyiouka, S. N., Karakatsani, E. K. and Papaspyrides, C. D, “Solid State Polymerization”, Prog. Polym. Sci., 30, 1037 (2005) 10.1016/j.progpolymsci.2004.11.001Search in Google Scholar

Woo, B. G., Choi, K. Y. and SongK.H., “Melt Polycondensation of Bisphenol A Polycarbonate by Forced Gas Sweeping Process II. Continuous Rotating-Disk Reactor”, Ind. Eng. Chem. Res., 40, 34593466 (2001) 10.1021/ie000908ySearch in Google Scholar

Xi, Z., Zhao, L. and Liu, Z., “New Falling Film Reactor for Melt Polycondensation Process”, Macromol. Symp., 259, 1016 (2007) 10.1002/masy.200751302Search in Google Scholar

Xiao, L., Wang, H., Qian, Q., Jiang, X., Liu, X., Huang, B. and Chen, Q., “Molecular and Structural Analysis of Epoxide-Modified Recycled Poly(ethylene terephthalate) from Rheological Data”, Polym. Eng. Sci., 10, 21272133 (2012) 10.1002/pen.23175Search in Google Scholar

Zhang, X., Li, H., Chen, W. and Feng, L., “Rheological Properties and Morphological Evolutions of Polypropylene/Ethylene-butene Copolymer Blends”, Polym. Eng. Sci., 52, 17401748 (2012) 10.1002/pen.23116Search in Google Scholar

Received: 2015-06-16
Accepted: 2016-04-03
Published Online: 2016-06-23
Published in Print: 2016-07-30

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