PTC effect in HDPE filled with carbon blacks modified by Ni and Au metallic particles

Abstract

Several types of positive temperature coefficient (PTC) composites are prepared by using Ni and Au modified carbon black. The major aim of this work was the lowering of the room temperature resistivity of the composites by enhancement of electrical conduction of the CB particles by incorporating metallic particles. Investigations showed that the metal particles fill the cavities and surface defects of the CB and thus surface free area reduces after modification. Metallic particles also change the nature of the CB particles after modification. Several types of PTC composites were prepared by using modified and unmodified CB by several loading level of filler. Measuring electrical properties of the PTC samples showed that the Ni modified CB reduce room temperature resistivity to lower than that of PTC composites prepared by unmodified CB. PTC composites prepared by Au modified CBs showed very different properties compared to PTC composites prepared by Ni modified CB. Their resistivities were quite higher than the others showing a poor compatibility between the matrix and Au modified CB. The effect of thermal annealing also investigated on the electrical properties of the prepared composites. Room temperature resistivities reduced for most of the samples while PTC intensities increased after annealing. Theoretical bases are employed to discuss the room temperature resistivity and PTC behavior of the composites before and after annealing.

One‐step preparation of black polystyrene particles via in situ suspension polymerization

“…Carbon black (CB)/polystyrene (PS) composites have widespread applications in chemical gas sensor [1], positive temperature coefficient materials [2–4], and conductive material [5–7]. There are many reports with respect to the preparation of composites consisting of ultrafine inorganic particles and polymers.…”

Strong Metal–Support Interaction: Growth of Individual Carbon Nanofibers from Amorphous Carbon Interacting with an Electron Beam

“…It can be seen that the sequence of variation of the volume resistivity is 20 wt% CB > 25 wt% CB > 25% CB + c‐MWNTs, according to expectations. The introduction of c‐MWNTs into the HDPE/CB (75/25) composite resulted in a large reduction in the resistivity because of the known electronic properties of the c‐MWNTs 6. Interestingly, a marked reduction in the resistivity of the composites is found for small quantities of c‐MWNTs in the range 0.5–1.5 wt%.…”

“…for a given value of filler content, a sharp transition from the conductive to the insulating state or vice versa occurs. It is interesting to note that a filled semicrystalline polymer exhibits a positive temperature coefficient of resistance (PTC), which has a reversible character 6–8. The PTC effect on material properties has also attracted much attention in recent years because of the prospects of many applications, such as in temperature sensors, thermistors, self‐regulating heaters, etc 9, 10.…”

Surface modification of carbon black to facilitate suspension polymerization of styrene and carbon black

“…Polystyrene (PS), a general‐purpose thermoplastic, has been widely applied in various fields such as food packaging, positive temperature coefficient materials, conductive material, and chemical gas sensors . Especially, polystyrene as heat insulator has been widely used for external heat insulation in recent years.…”