ORIGINAL PAPER Improving rheological properties of covalently MWCNT/epoxy nanocomposites via surface re-modification Babak Kaffashi • Amir Kaveh • O. Moini Jazani • M. R. Saeb Received: 14 December 2010 / Accepted: 15 January 2012 / Published online: 8 February 2012 Ó Springer-Verlag 2012 Abstract This article describes the application of the chemical surface re-modi- fication of carboxylated multi-walled carbon nanotubes (MWCNTs) through in-situ esterification of oligomeric unsaturated aliphatic hydroxyl terminated polyesters. The Fourier transform infrared spectroscopy and the thermogravimetric analysis proved covalent treatment of MWCNTs. Consequently, the acid–base titration method was employed to determine the population of the re-modified sites within the polyester chains. The dispersion state of the re-modified MWCNTs was investigated by the transmission electron microscopy relevant to the cured nano- composite sample along with the Ultraviolet–Visible spectroscopy while using various solvents. The degree of dispersion was correlated to the Hansen solubility parameters. In summary, our study shows an appropriate dispersion of the re- modified MWCNTs into the solvents with a high dispersive fashion. In addition, the rheological properties of the re-modified MWCNTs/epoxy resin having various nanoinclusions were considerably studied and discussed. Also, an improved rheo- logical response was observed in the case of the re-modified MWCNT nanocom- posite samples. Keywords Rheological properties Á MWCNT/epoxy nanocomposites Á Surface re-modification B. Kaffashi (&) Á A. Kaveh School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran e-mail: kaffashi@ut.ac.ir O. Moini Jazani Á M. R. Saeb Department of Polymer and Color Engineering, Amir Kabir University of Technology, Tehran, Iran O. Moini Jazani Department of Chemical Engineering, College of Engineering, University of Isfahan, Isfahan, Iran 123 Polym. Bull. (2012) 68:2187–2197 DOI 10.1007/s00289-012-0707-0