Complex conductivity measurement of CNT/Polymer films using a non-contact microwave technique

N. Badi, V. Kanakadandila, J. Wosik, F. Chouit, S. Boukhezar, O. Guellati, M. Guerioune
University of Houston, US

Keywords: CNT/polymer composites, complex conductivity, dielectric permittivity, percolation network, non-contact microwave measurements


Carbon nanotubes (CNTs) reinforced composites have applications in electronics, optoelectronics, photovoltaic, sensors, structural materials, and energy storage systems. Electrical characteristics, such as alternating current (AC) complex conductivity and dielectric permittivity are key functional parameters of these materials. Measurement methods need to be optimized to obtain data to further enhance the quality control and manufacturing process. This paper reports on successful synthesis of pristine CNT materials and HDPE/CNTs composites by CCVD and Melt Processing techniques, respectively. This includes CNT/composite samples produced by uniform dispersion of up to 1% of MWCNTs in Grade TR144 HDPE polymer matrix (Figure 1) and samples made with thin films of MWCNTs deposited on the surface of a dielectric polymer layer (Figure 2). Elaborated samples were subjected to structural characterizations and complex conductivity measurements under a broad range of microwave frequencies (50 MHz to 12 GHz). Results on complex conductivity properties of composite materials with specific emphasis on reflected and transmitted non-contact microwave measurements will be presented and discussed. Preliminary data provides a way to distinguish between electromagnetic response of CNT/polymer samples to either microwave electric or to magnetic fields. As a result, percolation degree and screening efficiency of the different CNT-composite films were determined.