A study of viscoelastic properties of graphite (GP) filled high density polyethylene composites was carried out.The Mooney equation was modified to evaluate the formation and development of agglomerate structure for high filled suspension system.The apparent filler concentration (φ) was substituted by the effective volume fraction

φeff.It is believed that in the case of high filler concentrations the viscoelastic properties of the composites are mainly related with φeff.Here

we define φeff＝fφ

in which f(f≥1) is the experiential factor of effective volume

corresponding to the microstructure with different relaxation time in HDPE/GP system.In the low φ region

the viscoelastic properties of the composites can be described by the original Mooney equation

while the viscoelastic properties of the high loading composites can be described by the modified Mooney equation considering the effective filler volume in the case of ω＝0.1 rad/s

experientially postulate f＝1.55.