Percolation Network Formation in Poly(4-vinylpyridine)/Aluminum Nitride Nanocomposites: Rheological, Dielectric, and Thermal Investigations

This work is concerned with several issues related to the rheological behavior of poly(4-vinylpyridine)/aluminum nitride (AlN) nanocomposites. The composites are prepared by solution processing combined with ultrasonication and magnetic stirring. To understand the percolated structure, the nanocomposites are characterized via a set of rheological, dielectric, and thermal conductivity analyses. The nanoparticle networks are sensitive to the steady shear deformation particularly at low shear rates, where a shear-thinning domain is observed. The rheological measurements revealed also that the activation energy is significantly lower at high nanofiller loadings suggesting stronger AlN interactions. The changes in the terminal behavior of shear moduli are the result of variations in composite elasticity determined by the percolation network. The flocculation and percolation thresholds estimated from the rheological moduli dependence on AlN loading are correlated with the dielectric constant values. Thermal conductivity is determined from a new theoretical model involving, besides the contribution of each phase, both percolation processes and the shape of the nanofiller. (C) 2013 Society of Plastics Engineers