Rheological Percolation Threshold in High-Viscosity Polymer/CNTs Nanocomposites

Polystyrene (PS)/multi-walled carbon nanotubes (CNT) nanocomposites have been prepared through melt mixing processing aiming at obtaining a uniform and homogeneous dispersion of the used nanoparticles within the polymeric matrix. Optical and scanning electron microscopy has been employed to determine the dispersion and distribution of CNTs at different length scales. Furthermore, the linear viscoelastic behavior of formulated nanocomposites has been deeply investigated. As a result of CNTs added, the nanocomposites experience a transition from liquid-like to solid-like rheological behavior, and a disappearance of relaxation processes at low frequency can be noticed. By plotting G' versus CNTs loading and fitting with a power-law function, the rheological threshold of PS-based nanocomposites has been calculated. Moreover, the mechanical behavior of nanocomposites has been investigated and related to the formed CNTs network within polymer matrix. (C) 2016 American Society of Civil Engineers.