Prof. John Zhanhu Guo
Prof. John Zhanhu Guo
University of Tennessee, USA
Title: Anticorrosive conductive polyurethane multiwalled carbon nanotube nanocomposites
In the present study, conductive polyurethane (PU) nanocomposite coatings filled with multiwalled carbon nanotube (MWNTs) prepared via an in situ surface-initiated-polymerization method were evaluated for anticorrosion purpose. Scanning electron microscopy (SEM) reveals a uniformly dispersed MWNTs nanoparticles in the PU matrix. Thermogravimetric analysis (TGA) shows an enhanced thermal stability of the composite as compared to pure PU. The nanocomposite exhibits a good response of electrical conductivity change to the varying strain during the cyclic strain test. The anticorrosion tests in 3.0 wt% NaCl aqueous solution suggest that the composite coatings possess a good chemical stability over long immersion time in the corrosive environment. A significantly positive shift of nearly 1.0 V in the open current potential (Eocp) was observed from the E -time curve of MWNTs/PU composite-coated stainless steel electrode. Extrapolation of Tafel plots gave a much more positive corrosion potential (Ecorr) and much lower corrosion current (Icorr). A protection efficiency as high as 97.70% was obtained. Electrochemical impedance spectroscopy (EIS) was conducted as well to investigate and obtain the anticorrosion mechanism of the composite coating. An equivalent circuit of the coating was proposed to fit the EIS data, confirming an effective corrosion protection for the stainless steel. The results indicate that the polyurethane matrix combined with the well dispersed MWNTs reinforcements provides an effective physical barrier against the attack of corrosive ions in the solution for the stainless steel.
Dr. Guo, currently an Associate Professor in Chemical & Biomolecular Engineering Department of at the University of Tennessee Knoxville, obtained his Bachelor degree from Shan-dong University of Science and Technology (1996), Master degree from Beijing University of Chemical Technology (1999), and Ph.D. degree from Louisiana State University (2005). All the degrees were from Chemical Engineering. Before joining UTK, Dr. Guo was working in Lamar University from 2008-2014 as Assistant/Associate Professor in Dan F. Smith Department of Chemical Engineering. Meanwhile, Dr. Guo had received a three-year (2005-2008) postdoctoral training in the Mechanical and Aerospace Engineering Department at the University of California Los Angeles. Dr. Guo directs the Integrated Composites Laboratory (ICL) with more than 20 members and has authored/coauthored more than 400 peer-reviewed journal papers and five patents with a total citation over 15,000 and h-index of more than 70. The scientific results have been reported by major media including Nanotechweb by the Institute of Physics (IOP), Plastics Engineering Magazine by the Society of Plastics Engineering (SPE), MaterialsViews by Wiley, National Science Foundation (NSF), etc. Dr. Guo has received Honorary Nomination Award of 2007 for UCLA-Chancellor Research, University Merit Award of 2012 for teaching, and University Scholar Award of 2013 for research at Lamar University. Dr. Guo had served as Chair for the Composites Division of AIChE (2011-2012). Dr. Guo’s current research team focuses on multifunctional light-weight nanocomposites, especially with polymer and carbon as the hosting matrix to solve the energy and sustainability issues. Currently, Dr. Guo is the editor-in-chief of Advanced Composites and Hybrid Materials and deputy editor of Engineered Science.