Stability of polymer composites as positive‐temperature‐coefficient resistors

Meyer, John C.

doi:10.1002/pen.760141009

Cited by 199 publications

(131 citation statements)

References 16 publications

Supporting

Mentioning

130

Contrasting

Order By: Relevance

“…2 The PTC effect can be a t least partly explained by rapid expansion of the system undergoing melting, thereby increasing the gaps between particles and aggregates and thus hindering the process of electron tunneling. The ratio of crystalline to amorphous material constituting these gaps decreases with progress of the melting process, causing additional resistance in them (amorphous polymer being less conductive than its counterpart crystalline form6).…”

mentioning

confidence: 99%

Effect of crosslinking on carbon black/polyethylene switching materials

Narkis

Ram

Stein

1980

J of Applied Polymer Sci

105

View full text Add to dashboard Cite

Electrical conductivity in insulating polymeric materials can be achieved by incorporation of dispersible conducting Carbon black, a common conducting filler for elastomers and plastics, can impart antistatic and semiconducting properties to these materials depending on the specific type and its concentration. The electrical conductivity of carbon black is influenced by its particle size, aggregate shape and structure, porosity, and surface chemistry. The electrical conductivity of carbon black/polymer mixtures depends also on polymer characteristics such as chemical structure and crystallinity, and on processing methods and processing conditions. Improved conductivity of polymer/carbon black mixtures is achieved by using carbon black of smaller particle size (larger surface area), lower particle density (higher particle porosity), higher structure (better aggregation), and low volatility (fewer chemisorbed oxygen groups). Conductive carbon blacks such as Vulcan XC72 (Cabot Corp., MA) and Ketjenblack EC (Akzo Chemie, The Netherlands) having

show abstract

mentioning

confidence: 99%

Effect of crosslinking on carbon black/polyethylene switching materials

Narkis

Ram

Stein

1980

J of Applied Polymer Sci

105

View full text Add to dashboard Cite

show abstract

“…In this sense, PMo 12 would be acting as a catalyst in air, which confirms the ability of PMo 12 to oxidize EDOT to PEDOT in the absence of any other reagent. SEM micrographs of the phosphomolybdic acid and of the chemically synthesized temperature from $2.0 to 7.0 S cm À1 between 300 and 400 K. It accounts for the expected thermally activated behavior of the hybrid material having p-type polaronic conductivity [18].…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Novel Organo‐Inorganic Hybrid Material of Poly(3,4‐Ethylene Dioxythiophene) and PhosphomolybdateAnion

Murugan

Kwon

Campet

et al. 2002

Active and Passive Electronic Components

View full text Add to dashboard Cite

The organo‐inorganic hybrid material, consisting of Poly(3,4‐Ethylene Dioxythiophene) (PEDOT) doped with phosphomolybdate cluster anions , has been synthesized by direct in situ oxidative polymerization of 3,4‐Ethylene Dioxythiophene (EDOT) with phosphomolybdic acid (H3PMo12O40) . Its characterization is investigated by Fourier Transform Infrared Spectroscopy (FT‐IR) and Scanning Electron Microscopy (SEM). The hybrid material presents predominantly high electronic conductivities of around 2.0 and 7.0 S cm−1 at 300 and 400K respectively.

show abstract

“…This phenomenon is caused by the two factors, the interparticle distance and the number of conductive paths. 6,20,21 The large thermal expansion of the polymer matrix can significantly increase the interparticle distance and reduce the number of conductive paths. According to the tunneling theory, the tunneling probability of an electron is related to the interparticle distance.…”

Section: Resultsmentioning

confidence: 99%

“…This phenomenon is referred to as the negative temperature coefficient (NTC) effect. 6,7 In general, non-crosslinked CB-filled semicrystalline polymer composites cannot be used as thermistors in over-temperature and over-current protections due to their NTC effects and poor reproducibility in thermal recycling. To overcome these disadvantages, researchers have proposed and developed many methods to eliminate the NTC effect of CB-filled semicrystalline polymer composites.…”

mentioning

confidence: 99%

Electrical Properties of Non-Crosslinked Polyethylene/Syndiotactic Polystyrene Composites Filled with Carbon Black

Yoon

Lee

Choi

et al. 2007

Polym J

View full text Add to dashboard Cite

ABSTRACT:Carbon black (CB)-filled high density polyethylene (HDPE)/syndiotactic polystyrene (sPS) composites were prepared by the conventional melt-mixing procedure. The effect of the HDPE/sPS weight ratio, CB content and processing speed on the thermoelectric behavior such as positive temperature coefficient (PTC) and negative temperature coefficient (NTC) was investigated in detail. The non-crosslinked HDPE/sPS composites containing 10-phr CB, a typical PTC behavior was observed when the temperature increased toward the melting point of HDPE. At high processing speed, the composites exhibited high room temperature resistivity and high PTC intensity. In a high sPS content composite, the dispersion of sPS particles are homogeneous and the distance of sPS particles are very close. The CB-coated sPS particles could be formed a continuous conductive network; therefore the PTC effect became weaker and weaker in these systems. The elimination of the NTC effect in CB-filled composites can be achieved by using a very high melting semicrystalline polymer as one of its components. An interesting phenomenon exhibited by the some conductive polymer is a positive temperature coefficient (PTC) effect. The main feature of PTC materials is that heating causes the conductive system to show a sharp resistivity increase near the melting region of a semicrystalline polymer matrix. 1,2A well-known technique that brings conducting properties into an intrinsically insulating polymer incorporates it with conducting fillers such as carbon black, 3 metal powder and fibers 4 or graphite fibers. 5Although metal powders are intrinsically more conductive than carbon black, metal has a tendency to oxidation to form an insulating layer on its surface and is not used as frequently as carbon back (CB). One of the most common additives used in conducting polymers is CB, which initially forms isolated structures within the matrix; then isolated clusters form, and finally through-going paths arise.The critical amount of CB necessary to form a conductive network is referred to as the percolation threshold. It is desirable for the conducting filler content to be as low as possible to achieve good processability, good mechanical properties and low cost.It is well known that when the temperature is above the melting point of semicrystalline polymers, noncrosslinked CB-filled semicrystalline polymer composites exhibit a very sharp decrease in resistivity. This phenomenon is referred to as the negative temperature coefficient (NTC) effect. 6,7 In general, non-crosslinked CB-filled semicrystalline polymer composites cannot be used as thermistors in over-temperature and over-current protections due to their NTC effects and poor reproducibility in thermal recycling. To overcome these disadvantages, researchers have proposed and developed many methods to eliminate the NTC effect of CB-filled semicrystalline polymer composites. Among these methods, the approach used to crosslink the semicrystalline polymer matrix by a crosslinking agent, such as a peroxide 8...

show abstract

Stability of polymer composites as positive‐temperature‐coefficient resistors

Cited by 199 publications

References 16 publications

Effect of crosslinking on carbon black/polyethylene switching materials

Effect of crosslinking on carbon black/polyethylene switching materials

Synthesis and Characterization of Novel Organo‐Inorganic Hybrid Material of Poly(3,4‐Ethylene Dioxythiophene) and PhosphomolybdateAnion

Electrical Properties of Non-Crosslinked Polyethylene/Syndiotactic Polystyrene Composites Filled with Carbon Black

Contact Info

Product

Resources

About