Rheological properties and percolation of high-density polyethylene filled with graphites having different topological parameters

The studies concerning the influence of particle parameters such as size, shape and concentration on the rheological properties of graphite (GP) filled high-density polyethylene (HDPE) composites were carried out by using two kinds of GP with different shape and size distribution of the particles. Upon the critical concentration of fillers, the dynamic storage modulus G' remarkably increases and exhibits a "pseudo solid-like" behavior within the lower frequency region. These phenomena are assumed the characteristics of percolated network structure formed by the filler particles. The values of the threshold for two kinds of HDPE/GP composites are also evaluated. It is proved that the smaller was the specific surface of particles dispersed in the composite, the lower the thresholds. It is found that there exists correspondence between the morphology and the percolation phenomena of the rheological behavior for these composites. It is suggested that different topological parameters of two kinds of GP particles result in different percolation mechanism.