I-V characteristics of carbon black-loaded crystalline polyethylene

Al‐Allak, H. M.; Brinkman, A.W.; Woods, J.

doi:10.1007/bf00349041

Cited by 91 publications

(24 citation statements)

References 7 publications

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“…[5][6][7] The former makes the materials have a wide range of conductivity from insulator to semiconductor, depending on CB concentration. The latter is characterized by either positive temperature coefficient (PTC) effect or negative temperature coefficient.…”

Section: Introductionmentioning

confidence: 99%

“…The latter is characterized by either positive temperature coefficient (PTC) effect or negative temperature coefficient. Many models have been proposed for explaining the mechanisms involved in both PTC and negative temperature coefficient phenomena, such as thermal expansion, 8 electron tunneling, 9 -11 thermal fluctuation-induced tunneling, 12 cooperative effect of changes in crystallinity and volume expansion, 5 and double percolation. 13,14 For a polymer-based PTC material of practical value, its volume resistivity increases remarkably by several orders of magnitude when temperature approaches to the melting point of matrix resin.…”

Section: Introductionmentioning

confidence: 99%

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Carbon-black-filled polyolefine as a positive temperature coefficient material: Effect of composition, processing, and filler treatment

Yu¹,

Zhang²,

Zeng³

1998

J. Appl. Polym. Sci.

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ABSTRACT:Polymer-based positive temperature coefficient (PTC) composites are of special interest because they have great potential in temperature-sensitive devices. To obtain a reproducible PTC composite with acceptable PTC intensity, effect of conductive filler content, processing conditions and filler treatment with nitric acid, and titanate coupling agents on room temperature resistivity and PTC intensity of carbon-blackfilled low-density polyethylene composites have been described and discussed herein. The results showed that filler arrangement is a key factor influencing the ultimate material performance, which can be tailored in various ways.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carbon-black-filled polyolefine as a positive temperature coefficient material: Effect of composition, processing, and filler treatment

Yu¹,

Zhang²,

Zeng³

1998

J. Appl. Polym. Sci.

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“…These can be attributed to the variation of conduction mechanism in various loading of CB content. At high CB loadings, the CB particles and their aggregates directly contact with one another even at the temperatures above the T m of PTFE, resulting in a main conduction mechanism of ohmic conduction [24]. The expansion of PTFE particles would only decrease the dimensions of the conductive pathways but not break them up, so the PTC effect of these composites with high CB contents was very weak and got even weaker with the increasing of the CB concentration.…”

Section: Resultsmentioning

confidence: 99%

Positive temperature coefficient effects of carbon blackfilled polytetrafluoroethylene composites

2009

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Carbon black (CB)-filled polytetrafluoroethylene (PTFE) composites were prepared by compact molding of a dry-mixture of CB and polymer powders followed by a sintering technology. The composites show a very low percolation threshold about 5 vol. %, which can be attributed to the segregated distribution of CB in the interfacial regions of PTFE particles. The PTFE/CB composites exhibit a high PTC transition temperature (>300 0 C), high PTC intensity (3.5) and no NTC effects. The absence of NTC effect of the composites was attributed to the extremely high viscosity of PTFE at temperatures above its melting point, which restricts the migration of CB particles and prevents the formation of new conductive networks.

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“…9 The interfacial adhesion and physical properties of these resulting blends can be improved by the addition of compatibilizing agents such as copolymer, 10,11 through grafting, 12 or crosslinking. 13 From the point of view of processability and product cost, the toughening of PP by simple blending with thermoplastics such as polyethylene 14 is of great interest as it does not significant lowers its tensile strength. Ultra high molecular weight polyethylene (UHMWPE) has unique properties such as high impact strength, high wear strength, high abrasion resistance, as well as lightweight.…”

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confidence: 99%

Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

Wang¹,

Zhou

Zhang

et al. 2002

Adv Polym Technol

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ABSTRACT:A novel vibration internal mixer was used to prepare polypropylene/ultra high molecular weight polyethylene PP/UHMWPE blends with two additional adjustable processing parameters (vibration frequency and vibration amplitude) as compared with those prepared in the steady mode. Microscopy, mechanical tests, and differential scanning calorimetry showed that vibration influenced the blend morphology and the product properties. The good phase homogeneity of the blends might be due to the variation of shear rate either spatially or temporally in blending. Additionally, the vibration internal mixer could be used to analyze the dependency of viscosity on the shear rate. Vibration enhanced the interpenetration of UHMWPE into PP and vice versa. Subsequently, the formed crystals of two components were connected, and there was epitaxy MODIFICATION OF POLYPROPYLENE BY MELT VIBRATION BLENDINGbetween PP and UHMWPE crystals. Moreover, the crystalline aggregates, with the amorphous UHMWPE, formed a complex network-like continuous structure, which improved the elongation ratio at the break and the yield strength. The higher the vibration frequency and/or the larger the vibration amplitude at a fixed average rotation speed of the mixer, the more significant these effects were. The larger amount of the connected crystals, especially of ␤ form of PP in the bulk ␣ form PP as well as with the continuous phase structure, led to a higher tensile properties of PP/UHMWPE vibration blended. C 2002 Wiley Periodicals, Inc.

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I-V characteristics of carbon black-loaded crystalline polyethylene

Cited by 91 publications

References 7 publications

Carbon-black-filled polyolefine as a positive temperature coefficient material: Effect of composition, processing, and filler treatment

Carbon-black-filled polyolefine as a positive temperature coefficient material: Effect of composition, processing, and filler treatment

Positive temperature coefficient effects of carbon blackfilled polytetrafluoroethylene composites

Modification of polypropylene by melt vibration blending with ultra high molecular weight polyethylene

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