Ultralow Electrical Percolation Research Articles

Strategies for interfacial localization of graphene/polyethylene‐based cocontinuous blends for electrical percolation

AbstractWe have investigated melt blending approaches to interfacial localization of few‐layer graphene in cocontinuous polymer blends with polyethylene as one of the components. When linear low‐density polyethylene (LLDPE)/polypropylene (PP) or high‐density polyethylene (HDPE)/polylactic acid (PLA) and graphene were mixed all together, graphene preferred polyethylene over PP or PLA. When PP and graphene were premixed and blended with polyethylene, some graphene was trapped at the blend interface but not enough to cover the large interfacial area. In contrast, an ultralow electrical percolation was achieved (< 0.1 vol%) in HDPE/PLA blend due to smaller interfacial area. In another approach, polystyrene was added as a tertiary minor component to HDPE/PLA blends. This continuous interfacial layer containing graphene led to a low electrical percolation threshold (< 0.2 vol%). From these investigations, we suggest general ways to reduce a percolation threshold by kinetic control of the morphology of cocontinuous polymer blends.

Ultralow electrical percolation in melt-compounded polymer composites based on chemically expanded graphite

It has been difficult to construct electrical percolation networks in melt-compounded polymer composites due to shear-induced network destruction, especially for low graphene content composites. To overcome this issue, here we employ chemically expanded graphite (CEG) to construct conductive networks in which the polymer molecules would penetrate into the inner part of CEG to form a polymer entrapped in CEG structure. This novel polymer entrapped in CEG structure is very useful for the effective charge transfer and further construction of conductive networks in the process of melt compounding. The final polymer composites exhibit an ultralow electrical conductive percolation threshold of 0.29 vol% after melt compounding which is almost among the lowest level compared with those of other melt-compounded polymer composites. Besides, the thermal conductivity of the composites is also significantly enhanced. This strategy here has provided a new way to maintain the conductive networks and decrease the electrical percolation threshold in the melt-compounded polymer composites through constructing polymer entrapped in conductive fillers structure.