Fractional Electrification of Polar Polymers

Medley, J. A.

doi:10.1038/1711077a0

Cited by 37 publications

(18 citation statements)

References 4 publications

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“…In 1902, Knoblauch observed that solid organic acids tended to become negatively charged and solid organic bases tended to become positively charged when these powders were shaken from a piece of filter paper; [23] he proposed a proton-transfer mechanism for contact electrification. Medley made similar observations with acidic and basic ion-exchange resins in 1953, [24] and Diaz proposed that a proton-transfer mechanism could explain the contact electrification of a wide range of insulating materials. [13] Protontransfer is, of course, a specific example of the more-general mechanism of ion transfer.…”

Section: Mechanisms Of Contact Electrification: Electron Transfer Vermentioning

confidence: 71%

“…Medley was the first to observe a correlation between the sign of the covalently bound ion and the charge acquired through contact electrification in his study of the contact electrification of ionexchange resins. [24] Diaz and co-workers made detailed studies of the contact electrification of ion-containing polymers. [31] The sign of charge that these materials acquired through contact electrification was always the same as the sign of the covalently bound ion.…”

Section: Experimental Evidence For the Transfer Of Mobile Ions Upon Cmentioning

confidence: 99%

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Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets

2008

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This Review discusses ionic electrets: their preparation, their mechanisms of formation, tools for their characterization, and their applications. An electret is a material that has a permanent, macroscopic electric field at its surface; this field can arise from a net orientation of polar groups in the material, or from a net, macroscopic electrostatic charge on the material. An ionic electret is a material that has a net electrostatic charge due to a difference in the number of cationic and anionic charges in the material. Any material that has ions at its surface, or accessible in its interior, has the potential to become an ionic electret. When such a material is brought into contact with some other material, ions can transfer between them. If the anions and cations have different propensities to transfer, the unequal transfer of these ions can result in a net transfer of charge between the two materials. This Review focuses on the experimental evidence and theoretical models for the formation of ionic electrets through this ion-transfer mechanism, and proposes--as a still-unproved hypothesis--that this ion-transfer mechanism may also explain the ubiquitous contact electrification ("static electricity") of materials, such as organic polymers, that do not explicitly have ions at their surface.

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Section: Mechanisms Of Contact Electrification: Electron Transfer Vermentioning

confidence: 71%

Section: Experimental Evidence For the Transfer Of Mobile Ions Upon Cmentioning

confidence: 99%

Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets

2008

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“…The rather desultory activity in this field died off almost completely about 1930, at which time-as indeed up to the present-it could be fairly said that no clear picture of either the qualitative or quantitative phenomena had emerged. But in the late 1940's, to a large extent stimulated by the demands of the textile and the plastics industries, attack on the problem was made anew; see, for example, references [1,3,6,7,8,9,10,12,13,21,23,26,27] . There is hope that present-day techniques and materials, coupled with the advances in theory of the solid state, will permit substantial advances in the understanding of this traditional subject.…”

Section: Introductionmentioning

confidence: 99%

Static Electrification of Filaments

Hersh

Montgomery

1955

Textile Research Journal

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In order to study the generation of charge on fibrous materials, an apparatus was constructed in which a fiber is held fixed while a second is rubbed across it under controlled mechanical and ambient conditions. It was found that the reproducibility was usually within ± 5% when the same two fibers were rubbed repeatedly; that the charge generated was dependent on the manner in which the materials were rubbed; and that the magnitude of the charge generated was directly proportional to the length of material rubbed and to the normal force between the fibers (although in some cases a limiting maximum value was reached), but was independent of the apparent area of contact between the fibers and of the tension on the fibers. The effects produced by changes in velocity are more complicated to describe. Charge transfer was found to be independent of velocity when insulators (except Teflon) were rubbed together. For metals on insulators other than Teflon, the charge generated was found to increase linearly with velocity until a limiting value was reached, and then to remain constant. When Teflon and metals were rubbed together, the charge increased linearly with velocity without reaching a maximum. When Teflon was rubbed with insulators, the charge increased linearly with velocity in some cases but remained constant in others. A study of the dependence of the sign and amount of charge transferred on the nature of the materials rubbed was undertaken, and a triboelectric series was established. For metals on insulators, the amount of charge generated was found to be related to the work function of the metal and the position of the insulator in the triboelectric series. For insulators rubbed on insulators, the amount of charge transferred appeared to be independent of the positions of the insulators in the series.

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“…2, is in good agreement with the position of the materials in the triboelectric series. Two mechanisms that have been proposed to explain the characteristic net charging of different insulating materials upon contact in the presence of an adsorbed water bridge are as follows: first, by proton exchange between acidic or alkaline surfaces, with acidic surfaces acquiring negative net charge and alkaline surfaces positive net charge; [21][22][23][24] and second, by asymmetric partitioning of hydroxide ions. 14 This effect may be strongest for two materials with low and high water permeation or uptake, forming a negatively charged, sharp adsorbed-water/polymer interface for the hydrophobic material and a less charged, diffuse adsorbed water/polymer interface for the water-absorbing material.…”

Section: H Net Charging Mechanisms and Classification Of Triboelectrmentioning

confidence: 99%

Squeezing out hydrated protons: low-frictional-energy triboelectric insulator charging on a microscopic scale

Knorr¹

2011

AIP Advances

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Though triboelectric charging of insulators is common, neither its mechanism nor the nature of the charge is well known. Most research has focused on the integral amount of charge transferred between two materials upon contact, establishing, e.g., a triboelectric series. Here, the charge distribution of tracks on insulating polymer films rubbed by polymer-covered pointed swabs is investigated in high resolution by Kelvin probe force microscopy. Pronounced bipolar charging was observed for all nine rubbing combinations of three different polymers, with absolute surface potentials of up to several volts distributed in streaks along the rubbing direction and varying in polarity on μm-length scales perpendicular to the rubbing direction. Charge densities increased considerably for rubbing in higher relative humidity, for higher rubbing loads, and for more hydrophilic polymers. The ends of rubbed tracks had positively charged rims. Surface potential decay with time was strongly accelerated in increased humidity, particularly for polymers with high water permeability. Based on these observations, a mechanism is proposed of triboelectrification by extrusions of prevalently hydrated protons, stemming from adsorbed and dissociated water, along pressure gradients on the surface by the mechanical action of the swab. The validity of this mechanism is supported by explanations given recently in the literature for positive streaming currents of water at polymer surfaces and by reports of negative charging of insulators tapped by accelerated water droplets and of potential built up between the front and the back of a rubbing piece, observations already made in the 19th century. For more brittle polymers, strongly negatively charged microscopic abrasive particles were frequently observed on the rubbed tracks. The negative charge of those particles is presumably due in part to triboemission of electrons by polymer chain scission, forming radicals and negatively charged ions

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Fractional Electrification of Polar Polymers

Cited by 37 publications

References 4 publications

Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets

Electrostatic Charging Due to Separation of Ions at Interfaces: Contact Electrification of Ionic Electrets

Static Electrification of Filaments

Squeezing out hydrated protons: low-frictional-energy triboelectric insulator charging on a microscopic scale

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