Remarkable selective localization of modified nanoscaled carbon black and positive temperature coefficient effect in binary-polymer matrix composites

Academic and industrial research groups are currently working on materials with high-quality positive temperature coefficient (PTC) effects. They are crucial for designing new switching sensors, self-regulating heaters and shielding structures. Such materials are in fact the basis for a new generation of cheap and large sensors. Here we present a robust and simple procedure to prepare binary-polymer matrix composites with strong PTC effect through melt-mixing and subsequent hot-pressing technology. The intuitive and detailed double-percolation structure is observed on the basis of morphological evidence. Modified nanoscaled carbon black (MNCB) is often selectively localized in one of the binary-polymer phases. When the volume ratio of the two polymers is very close to 1 : 1, we observe remarkable PTC intensity (PTCI), namely PTCI = 3.3 x 10(7) in MNCB-high density polyethylene/polypropylene (MNCB-HDPE/PP) and PTCI = 8.3 x 10(7) in MNCB-HDPE/polyvinylidene fluoride (MNCB-HDPE/PVDF). The process for the preparation of these binary-polymer matrix PTC composites is suitable for industrial mass production.