Influence of annealing on rheological and conductive behaviors of high-density polyethylene/carbon black composites

A simultaneous measurement on dynamic viscoelastic and conductive behaviors was carried out to investigate the effect of high temperature annealing on the properties of carbon black (CB) filled high-density polyethylene composites. The results showed that dynamic storage and loss moduli of the composites increased significantly with increasing annealing time, and there existed a liquid- to solid-like transition at a critical time (t_c) which is dependent on temperature and CB content. Accompanying with the variation in dynamic moduli, electrical resistance (R) decreased sharply with time. What’s more, the increase of R could be observed in the long time region. The activation energy determined from t_c as a function of reciprocal temperature was found to be irrespective of CB content. The evolutions of moduli and R induced by thermal treatment were discussed on the base of the concept of filler flocculation in the melt.