Study On Properties Of Carbon Black/Polyolefin Conduction Composites

Electrical polymer conductive composite is a kind of functional materials which raised more and more focuses in recent years. In this paper, electrical polymer conductive composite was fabricated by melt mixing between CB (ACET CB,HG-1P) and polyolefin (PP,PE). On the one hand, effects of blending process, the distribution state of CB, CB content (mass fraction), heat treatment on resistivity and mechanical properties of CB/PP composites were studied. On the other hand, the distribution state of each component, resistivity and mechanical properties of CB/PE/PP composites were investigated in this paper.It is shown that resistivity of CB/PP composites decreased firstly and then increased as the blending temperature is raised or the blending time is increased. Blending temperature is the main factor to the dispersion of CB, forming ability and defect of sample, higher or lower of which will weaken its conductivity. With the increase of blending time, CB dispersed in the matrix of CB/PP composites is more uniform. But if the blending time extended more, the cutting effect of composite system among roll shafts destroys the dispersion shape of CB, which can lead to bad conductivity. Therefore, the optimum conductivity occurs when the blending temperature is 175℃and the blending time is 15 minutes.Resistivity of CB/PP composite material nonlinearly descends with the increase of the CB capacity, and the typical seepage conduction behavior emerges at such a circumstance. It is found from SEM photos of CB/PP composites that the distribution form of CB particles transforms from the sharp of "takeshima" to "grasp string", and finally changes into conductive network with the increasing the capacity of ACET CB. When CB capacity gets 20%, the dispersion form of HG-1P is better than ACET CB. When the capacity of carbon black is less than 30%, the conductivity of PP composite material filled with HG-IP is much better than that filled with acetylene carbon black. After the heat treatment, the conductivity has improved a lot. With the increase of the CB capacity, the tensile strength and impact strength of the composites reach the peak at the capacity of 20% CB, and then decrease. At the same time, elongation falls down but Young's modulus rises all along.Compared to the single matrix material, the conductivity of CB/PE/PP composites is better. CB of CB/PE/PP composites as the "necklace" shape selectively distributes in the phase boundary among the PE, PE and PP. It is found that the conductivity of CB/PE/PP composites with 70% PP capacity is best. Sawtooth appears in the impact strength of CB/PE/PP composites when the capacity of the PP increases. The impact strength of CB/PE/PP composites with 70% pp capacity reaches the maximum 67.73 kJ/m2, which is 62.03% larger than that in the CB/PP composites. It is displayed form the fracture photos of SEM that brittle fracture occurs in 30% PP capacity CB/PE/PP composites and while ductile fracture occurs in 70% PP capacity CB/PE/PP composites.