Conductive polymer blends filled with carbon black: Positive temperature coefficient behavior

Yu, Gang; Zhang, Ming Qiu; Zeng, Han; Hou, Yan Hui; Zhang, Hai Bo

doi:10.1002/pen.11562

Cited by 49 publications

(27 citation statements)

References 17 publications

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“…16 The affinity or interaction of CB to EMA, which is also a key factor to determine the distribution of CB in immiscible blends, is just available when the melt viscosities of the two polymers are comparable. 17 In our system, the melting viscosities of LLDPE and EMA differ greatly from each other, as shown by the complex viscosity in Figure 4. LLDPE exhibits smaller viscosity than EMA over a wide range of shear rate.…”

Section: Resultsmentioning

confidence: 95%

Morphology and electrical properties of carbon black filled LLDPE/EMA composites

Zhou

et al. 2006

J of Applied Polymer Sci

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The morphology and electrical properties of linear low density polyethylene (LLDPE)/poly (ethylenemethyl arylate) (EMA) blends filled with carbon black (CB) are investigated in this work. Comparing to LLDPE/CB composite, the higher percolation threshold of EMA/CB composite is attributed to the good interaction between EMA and CB. However, carbon black is found to locate preferentially in the LLDPE phase of LLDPE/EMA immiscible blends from the characterization of SEM and electrical properties, which greatly decreases the percolation threshold of the composites. The viscosity of the two polymers is the key factor to determine the distribution of CB instead of interfacial energy in this system. This suggests a method to control the distribution of CB in the immiscible blends by choosing the viscosity ratio of polymer blend.

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Section: Resultsmentioning

confidence: 95%

Morphology and electrical properties of carbon black filled LLDPE/EMA composites

Zhou

et al. 2006

J of Applied Polymer Sci

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“…• C. Yu et al 83 studied the PTC effect of blends made by LDPE and EVA. Based on the concept of double percolation and two-step percolation, PTC compositions with balanced performance, improved processability and reproducibility could be made.…”

Section: Carbon Black In Polymer Blendsmentioning

confidence: 98%

Carbon black filled conducting polymers and polymer blends

2002

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ABSTRACT:The objective of this article was to review the use of carbon black (CB) as a conductive filler in polymers and polymer blends. Important properties of CB related to its use in conducting polymers are discussed. The effects of polymer structure, molecular weight, surface tension, and processing conditions on electrical resistivity and physical properties of composites are discussed. Several percolation models applicable to CB/polymer blends are reviewed. Emphasis is placed on recent trends using polymer blends as the matrix to obtain conducting composites at a lower CB loading. A criterion for the distribution of CB in polymer blends is discussed.

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“…It should be stated at the very beginning that a lower room-temperature resisitivity, ensuring sufficient electrothermal output and a higher PTC intensity (the ratio of the maximum resistivity to the room-temperature resistivity calculated from the temperature dependence of composite resistivity), which prevents the material from overheating, is always expected. 15 This can serve as an assessment criterion of heat treatment besides the consideration based on cost effectiveness.…”

Section: Effect Of Heat Treatment On the Structure-property Relationsmentioning

confidence: 99%

“…5 Crosslinking of the matrix polymers can effectively eliminate the NTC effect by forming a network and reducing movement of the CB particles, 6 but the problem of performance stabilization becomes more complicated due to the introduction of the crosslinked structure. To improve the composites' electrical reproducibility, efforts have been made in two directions by our group: (1) The processing window was broadened by using immiscible polymer blends, instead of a single polymer, to realize a two-step percolation, 7,8 and (2) the conditions of post-heat treatment were optimized based on a careful investigation of morphological variations in the polyblends. 9 In fact, heat treatment of a composite has an important influence on a series of factors related to the electrical properties, [10][11][12] such as crystallinity, crystalline size, and filler distribution.…”

Section: Introductionmentioning

confidence: 99%

Improvement of conductive network quality in carbon black‐filled polymer blends

Hou¹,

Zhang²,

Rong³

et al. 2002

J of Applied Polymer Sci

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Heat treatment of polymer-based composites is critical for the enhancement of both stability and long-term service life, especially when the materials function under an inconstant temperature environment. The present article discusses the effect of heat-treatment conditions on the electrically conductive properties of carbon black (CB)-filled low-density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) composites, which are candidates for positive temperature coefficient (PTC) materials. It was found that the dispersion mode of CB particles changes as a function of the matrix morphology. When the composites are irradiated to form crosslinked networks in the matrix for the elimination of negative temperature coefficient (NTC) behavior, some of the produced free radicals are also entrapped for quite a long time after the irradiation treatment. These residual radicals further enhance the interaction between CB and the matrix and further induce the crosslinking of the matrix so that the composites' conductivity changes with time as a result of the continuous variation in the contacts between the conductive fillers. To improve the quality of the conduction paths in the composites, appropriate post-heat treatment should be carried out, which speeds up the formation of the above-mentioned two kinds of crosslinked structures within a limited time. Annealing at 75 o C for more than 10 h is believed to be an effective way. After the treatment, a balanced performance characterized by reduced roomtemperature resistivity and improved PTC intensity was obtained. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2768 -2775, 2002

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Conductive polymer blends filled with carbon black: Positive temperature coefficient behavior

Cited by 49 publications

References 17 publications

Morphology and electrical properties of carbon black filled LLDPE/EMA composites

Morphology and electrical properties of carbon black filled LLDPE/EMA composites

Carbon black filled conducting polymers and polymer blends

Improvement of conductive network quality in carbon black‐filled polymer blends

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