Conductive microfibril network

Based on the discussion above, it is clear that the amount and distribution of the CB particles on the surface of microfibrils are very critical factors to determine the percolation threshold of i-CB/PET/PE composite. When the CB content in the PET phase is just beyond the percolation threshold of CB/PET compound, the continuous network of CB particles may be formed inside the microfibrils. However, there are hardly any CB particles on the surface of the CB/PET microfibrils and there exists a pure polymer layer below the surface of CB/PET microfibrils. This results in a high contact resistance among the microfibrils. The whole system exhibits an insulator state though the electrically conductive microfibrils may form a network. As the CB content in the CB/PET microfibrils reaches max> fhe number of CB paxticles on the surface evidently increases. Conduction pathways axe formed between some contact points in the microfibril network. With a further increase of CB content, the amount of CB particles on the microfibril surface increased significantly, and the electrically conductive contact points also increased. When the number of contact points is large enough to form a network to sustain the electron transmission in the whole... 

Figure 13.8. The schematic illustration of microstructural development for the conductive microfibrillar network during thermal process. The gray and the black regions represent the cross sections of microfibrils and the CB aggregates, respectively, (a) At room temperature before heating (b) beyond the PTC region (c) after isothermal treatment at high temperature (d) cooling to room temperature again [19]...

As mentioned above, conductive network can be formed via fine contacts of aligned CB coated PET microfibrils. Additionally, the high t values suggest the existence of the tunneling conduction. Hence, contact conduction and tunneling conduction synergetically form the conductive networks of the ACPC material. 

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