Macromolecular Nanotechnology Effect of activated carbon black nanoparticles on solid state polymerization of poly(ethylene terephthalate) D.N. Bikiaris, D.S. Achilias, D.J. Giliopoulos, G.P. Karayannidis * Laboratory of Organic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Macedonia, Greece Received 19 April 2006; received in revised form 22 May 2006; accepted 19 July 2006 Available online 27 September 2006 Abstract Solid state polycondensation (SSP) is a conventional method used to increase the molecular weight of poly(ethylene terephthalate) (PET) in order to become more suitable for applications as carbonated soft drink bottles, etc. In the present study, the effect of activated carbon black (ACB) nanoparticles, on the SSP kinetics is examined. TEM micrographs revealed that ACB was finely dispersed into PET matrix as individual nanoparticles without creating agglomerates. Intrin- sic viscosity (IV) measurements revealed that at temperatures 210 and 220 °C the activated carbon black does not influence the IV increase. However, at 230 and 240 °C an accelerating effect was found and higher intrinsic viscosity values were measured, compared to neat PET. Furthermore, a simple kinetic model was employed to predict the time evolution of IV, as well as the carboxyl and hydroxyl content during SSP. The kinetic parameters of the transesterification and ester- ification reactions were estimated at different temperatures with or without the addition of ACB. From the experimental measurements and the theoretical simulation results it was proved that ACB enhances the esterification reaction at all stud- ied temperatures acting as a co-catalyst. However, the transesterification reaction remains unaffected by the presence of ACB at elevated temperatures (230 or 240 °C), while it is reduced at lower values (210 and 220 °C). Finally, the activation energies of both transesterification and esterification were determined together with the concentration of inactive end- groups. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Poly(ethylene terephthalate); Activated carbon black; Nanoparticles; Solid state polycondensation 1. Introduction Poly(ethylene terephthalate) is one of the most important engineering polymers because of its abil- ity to be oriented and molded in different forms. Typical properties in which PET differentiate itself from other engineering plastics include: extreme low water absorption, dimensional stability, resis- tance to chemicals, very good heat and ageing resis- tance, very low creep and very good color stability, together with its excellent electrical properties. Applications of PET can be found in packaging, fibers production, films, automotive and electronics [1]. 0014-3057/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2006.07.027 * Corresponding author. Tel.: +30 2310 997814; fax: +30 2310 997769. E-mail address: karayan@chem.auth.gr (G.P. Karayannidis). European Polymer Journal 42 (2006) 3190–3201 www.elsevier.com/locate/europolj EUROPEAN POLYMER JOURNAL MACROMOLECULAR NANOTECHNOLOGY