Dielectric properties of nanocomposites based on cellulose nanocrystals (CNCs) and poly(styrene-co-2-ethyl hexylacrylate) copolymer

In the present work, the dielectric properties of nanocomposites based on poly(styrene-Co-2-ethyl hexylacrylate) copolymer (StHA) and cellulose nanocrystals (CNCs) and gamma-methacryloxypropyl triethoxysilane (MPS) as a coupling agent were investigated. Four relaxation processes were detected: the beta relaxation, the alpha relaxation, the electrode polarization and the ionic conduction phenomenon. These two later were identified with the real part epsilon' and the imaginary part epsilon of the dielectric permittivity slopes. Moreover, the electrode polarization was spotted using the first derivative of the real part of the dielectric permittivity. The activation energy E-A for the beta relaxation, the strength parameter D for the alpha relaxation and the relaxation strength Delta epsilon showed a threshold value of 4% in weight of CNC. Variations were explained with attractive and repulsive cellulose-cellulose and cellulose-copolymer interactions. The electrical study confirmed the dielectric results indicating the higher conductivity for the nanocomposite with 4% w. t of CNC. This work provided additional evidence of the formation of a rigid percolation network via hydrogen bonding for nanocomposites based on CNCs. (C) 2017 Published by Elsevier Ltd.